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+#!/usr/bin/env python
+# Copyright (c) 2012 Trent Mick.
+# Copyright (c) 2007-2008 ActiveState Corp.
+# License: MIT (http://www.opensource.org/licenses/mit-license.php)
+
+r"""A fast and complete Python implementation of Markdown.
+
+[from http://daringfireball.net/projects/markdown/]
+> Markdown is a text-to-HTML filter; it translates an easy-to-read /
+> easy-to-write structured text format into HTML.  Markdown's text
+> format is most similar to that of plain text email, and supports
+> features such as headers, *emphasis*, code blocks, blockquotes, and
+> links.
+>
+> Markdown's syntax is designed not as a generic markup language, but
+> specifically to serve as a front-end to (X)HTML. You can use span-level
+> HTML tags anywhere in a Markdown document, and you can use block level
+> HTML tags (like <div> and <table> as well).
+
+Module usage:
+
+    >>> import markdown2
+    >>> markdown2.markdown("*boo!*")  # or use `html = markdown_path(PATH)`
+    u'<p><em>boo!</em></p>\n'
+
+    >>> markdowner = Markdown()
+    >>> markdowner.convert("*boo!*")
+    u'<p><em>boo!</em></p>\n'
+    >>> markdowner.convert("**boom!**")
+    u'<p><strong>boom!</strong></p>\n'
+
+This implementation of Markdown implements the full "core" syntax plus a
+number of extras (e.g., code syntax coloring, footnotes) as described on
+<https://github.com/trentm/python-markdown2/wiki/Extras>.
+"""
+
+cmdln_desc = """A fast and complete Python implementation of Markdown, a
+text-to-HTML conversion tool for web writers.
+
+Supported extra syntax options (see -x|--extras option below and
+see <https://github.com/trentm/python-markdown2/wiki/Extras> for details):
+
+* admonitions: Enable parsing of RST admonitions.
+* breaks: Control where hard breaks are inserted in the markdown.
+  Options include:
+  - on_newline: Replace single new line characters with <br> when True
+  - on_backslash: Replace backslashes at the end of a line with <br>
+* break-on-newline: Alias for the on_newline option in the breaks extra.
+* code-friendly: Disable _ and __ for em and strong.
+* cuddled-lists: Allow lists to be cuddled to the preceding paragraph.
+* fenced-code-blocks: Allows a code block to not have to be indented
+  by fencing it with '```' on a line before and after. Based on
+  <http://github.github.com/github-flavored-markdown/> with support for
+  syntax highlighting.
+* footnotes: Support footnotes as in use on daringfireball.net and
+  implemented in other Markdown processors (tho not in Markdown.pl v1.0.1).
+* header-ids: Adds "id" attributes to headers. The id value is a slug of
+  the header text.
+* highlightjs-lang: Allows specifying the language which used for syntax
+  highlighting when using fenced-code-blocks and highlightjs.
+* html-classes: Takes a dict mapping html tag names (lowercase) to a
+  string to use for a "class" tag attribute. Currently only supports "img",
+  "table", "thead", "pre", "code", "ul" and "ol" tags. Add an issue if you require
+  this for other tags.
+* link-patterns: Auto-link given regex patterns in text (e.g. bug number
+  references, revision number references).
+* markdown-in-html: Allow the use of `markdown="1"` in a block HTML tag to
+  have markdown processing be done on its contents. Similar to
+  <http://michelf.com/projects/php-markdown/extra/#markdown-attr> but with
+  some limitations.
+* metadata: Extract metadata from a leading '---'-fenced block.
+  See <https://github.com/trentm/python-markdown2/issues/77> for details.
+* middle-word-em: Allows or disallows emphasis syntax in the middle of words,
+  defaulting to allow. Disabling this means that `this_text_here` will not be
+  converted to `this<em>text</em>here`.
+* nofollow: Add `rel="nofollow"` to add `<a>` tags with an href. See
+  <http://en.wikipedia.org/wiki/Nofollow>.
+* numbering: Support of generic counters.  Non standard extension to
+  allow sequential numbering of figures, tables, equations, exhibits etc.
+* pyshell: Treats unindented Python interactive shell sessions as <code>
+  blocks.
+* smarty-pants: Replaces ' and " with curly quotation marks or curly
+  apostrophes.  Replaces --, ---, ..., and . . . with en dashes, em dashes,
+  and ellipses.
+* spoiler: A special kind of blockquote commonly hidden behind a
+  click on SO. Syntax per <http://meta.stackexchange.com/a/72878>.
+* strike: text inside of double tilde is ~~strikethrough~~
+* tag-friendly: Requires atx style headers to have a space between the # and
+  the header text. Useful for applications that require twitter style tags to
+  pass through the parser.
+* tables: Tables using the same format as GFM
+  <https://help.github.com/articles/github-flavored-markdown#tables> and
+  PHP-Markdown Extra <https://michelf.ca/projects/php-markdown/extra/#table>.
+* toc: The returned HTML string gets a new "toc_html" attribute which is
+  a Table of Contents for the document. (experimental)
+* use-file-vars: Look for an Emacs-style markdown-extras file variable to turn
+  on Extras.
+* wiki-tables: Google Code Wiki-style tables. See
+  <http://code.google.com/p/support/wiki/WikiSyntax#Tables>.
+* wavedrom: Support for generating Wavedrom digital timing diagrams
+* xml: Passes one-liner processing instructions and namespaced XML tags.
+"""
+
+# Dev Notes:
+# - Python's regex syntax doesn't have '\z', so I'm using '\Z'. I'm
+#   not yet sure if there implications with this. Compare 'pydoc sre'
+#   and 'perldoc perlre'.
+
+__version_info__ = (2, 4, 14)
+__version__ = '.'.join(map(str, __version_info__))
+__author__ = "Trent Mick"
+
+import argparse
+import codecs
+import logging
+import re
+import sys
+from collections import defaultdict, OrderedDict
+from abc import ABC, abstractmethod
+import functools
+from hashlib import sha256
+from random import randint, random
+from typing import Dict, List, Optional, Tuple, Union
+from enum import IntEnum, auto
+
+if sys.version_info[1] < 9:
+    from typing import Iterable
+else:
+    from collections.abc import Iterable
+
+# ---- globals
+
+DEBUG = False
+log = logging.getLogger("markdown")
+
+DEFAULT_TAB_WIDTH = 4
+
+
+SECRET_SALT = bytes(randint(0, 1000000))
+# MD5 function was previously used for this; the "md5" prefix was kept for
+# backwards compatibility.
+def _hash_text(s):
+    return 'md5-' + sha256(SECRET_SALT + s.encode("utf-8")).hexdigest()[32:]
+
+# Table of hash values for escaped characters:
+g_escape_table = dict([(ch, _hash_text(ch))
+    for ch in '\\`*_{}[]()>#+-.!'])
+
+# Ampersand-encoding based entirely on Nat Irons's Amputator MT plugin:
+#   http://bumppo.net/projects/amputator/
+_AMPERSAND_RE = re.compile(r'&(?!#?[xX]?(?:[0-9a-fA-F]+|\w+);)')
+
+
+# ---- exceptions
+class MarkdownError(Exception):
+    pass
+
+
+# ---- public api
+
+def markdown_path(path, encoding="utf-8",
+                  html4tags=False, tab_width=DEFAULT_TAB_WIDTH,
+                  safe_mode=None, extras=None, link_patterns=None,
+                  footnote_title=None, footnote_return_symbol=None,
+                  use_file_vars=False):
+    fp = codecs.open(path, 'r', encoding)
+    text = fp.read()
+    fp.close()
+    return Markdown(html4tags=html4tags, tab_width=tab_width,
+                    safe_mode=safe_mode, extras=extras,
+                    link_patterns=link_patterns,
+                    footnote_title=footnote_title,
+                    footnote_return_symbol=footnote_return_symbol,
+                    use_file_vars=use_file_vars).convert(text)
+
+
+def markdown(text, html4tags=False, tab_width=DEFAULT_TAB_WIDTH,
+             safe_mode=None, extras=None, link_patterns=None,
+             footnote_title=None, footnote_return_symbol=None,
+             use_file_vars=False, cli=False):
+    return Markdown(html4tags=html4tags, tab_width=tab_width,
+                    safe_mode=safe_mode, extras=extras,
+                    link_patterns=link_patterns,
+                    footnote_title=footnote_title,
+                    footnote_return_symbol=footnote_return_symbol,
+                    use_file_vars=use_file_vars, cli=cli).convert(text)
+
+
+class Stage(IntEnum):
+    PREPROCESS = auto()
+    HASH_HTML = auto()
+    LINK_DEFS = auto()
+
+    BLOCK_GAMUT = auto()
+    HEADERS = auto()
+    LISTS = auto()
+    CODE_BLOCKS = auto()
+    BLOCK_QUOTES = auto()
+    PARAGRAPHS = auto()
+
+    SPAN_GAMUT = auto()
+    CODE_SPANS = auto()
+    ESCAPE_SPECIAL = auto()
+    LINKS = auto()  # and auto links
+    ITALIC_AND_BOLD = auto()
+
+    POSTPROCESS = auto()
+    UNHASH_HTML = auto()
+
+
+def mark_stage(stage: Stage):
+    '''
+    Decorator that handles executing relevant `Extra`s before and after this `Stage` executes.
+    '''
+    def wrapper(func):
+        @functools.wraps(func)
+        def inner(md: 'Markdown', text, *args, **kwargs):
+            md.stage = stage
+            # set "order" prop so extras can tell if they're being invoked before/after the stage
+            md.order = stage - 0.5
+
+            if stage in Extra._exec_order:
+                for klass in Extra._exec_order[stage][0]:
+                    if klass.name not in md.extra_classes:
+                        continue
+                    extra = md.extra_classes[klass.name]
+                    if extra.test(text):
+                        text = extra.run(text)
+
+            md.order = stage
+            text = func(md, text, *args, **kwargs)
+            md.order = stage + 0.5
+
+            if stage in Extra._exec_order:
+                for klass in Extra._exec_order[stage][1]:
+                    if klass.name not in md.extra_classes:
+                        continue
+                    extra = md.extra_classes[klass.name]
+                    if extra.test(text):
+                        text = extra.run(text)
+
+            return text
+
+        return inner
+
+    return wrapper
+
+
+class Markdown(object):
+    # The dict of "extras" to enable in processing -- a mapping of
+    # extra name to argument for the extra. Most extras do not have an
+    # argument, in which case the value is None.
+    #
+    # This can be set via (a) subclassing and (b) the constructor
+    # "extras" argument.
+    extras = None
+    # dict of `Extra` names and associated class instances, populated during _setup_extras
+    extra_classes = None
+
+    urls = None
+    titles = None
+    html_blocks = None
+    html_spans = None
+    html_removed_text = "{(#HTML#)}"  # placeholder removed text that does not trigger bold
+    html_removed_text_compat = "[HTML_REMOVED]"  # for compat with markdown.py
+
+    _toc = None
+
+    # Used to track when we're inside an ordered or unordered list
+    # (see _ProcessListItems() for details):
+    list_level = 0
+
+    stage: Stage
+    '''Current "stage" of markdown conversion taking place'''
+    order: int
+    '''
+    Same as `Stage` but will be +/- 0.5 of the value of `Stage`.
+    This allows extras to check if they are running before or after a particular stage
+    with `if md.order < md.stage`.
+    '''
+
+    _ws_only_line_re = re.compile(r"^[ \t]+$", re.M)
+
+    def __init__(self, html4tags=False, tab_width=4, safe_mode=None,
+                 extras=None, link_patterns=None,
+                 footnote_title=None, footnote_return_symbol=None,
+                 use_file_vars=False, cli=False):
+        if html4tags:
+            self.empty_element_suffix = ">"
+        else:
+            self.empty_element_suffix = " />"
+        self.tab_width = tab_width
+        self.tab = tab_width * " "
+
+        # For compatibility with earlier markdown2.py and with
+        # markdown.py's safe_mode being a boolean,
+        #   safe_mode == True -> "replace"
+        if safe_mode is True:
+            self.safe_mode = "replace"
+        else:
+            self.safe_mode = safe_mode
+
+        # Massaging and building the "extras" info.
+        if self.extras is None:
+            self.extras = {}
+        elif not isinstance(self.extras, dict):
+            self.extras = dict([(e, None) for e in self.extras])
+        if extras:
+            if not isinstance(extras, dict):
+                extras = dict([(e, None) for e in extras])
+            self.extras.update(extras)
+        assert isinstance(self.extras, dict)
+
+        if "toc" in self.extras:
+            if "header-ids" not in self.extras:
+                self.extras["header-ids"] = None   # "toc" implies "header-ids"
+
+            if self.extras["toc"] is None:
+                self._toc_depth = 6
+            else:
+                self._toc_depth = self.extras["toc"].get("depth", 6)
+
+        if 'header-ids' in self.extras:
+            if not isinstance(self.extras['header-ids'], dict):
+                self.extras['header-ids'] = {
+                    'mixed': False,
+                    'prefix': self.extras['header-ids'],
+                    'reset-count': True
+                }
+
+        if 'break-on-newline' in self.extras:
+            self.extras.setdefault('breaks', {})
+            self.extras['breaks']['on_newline'] = True
+
+        if 'link-patterns' in self.extras:
+            # allow link patterns via extras dict without kwarg explicitly set
+            link_patterns = link_patterns or extras['link-patterns']
+            if link_patterns is None:
+                # if you have specified that the link-patterns extra SHOULD
+                # be used (via self.extras) but you haven't provided anything
+                # via the link_patterns argument then an error is raised
+                raise MarkdownError("If the 'link-patterns' extra is used, an argument for 'link_patterns' is required")
+            self.extras['link-patterns'] = link_patterns
+
+        self._instance_extras = self.extras.copy()
+        self.link_patterns = link_patterns
+        self.footnote_title = footnote_title
+        self.footnote_return_symbol = footnote_return_symbol
+        self.use_file_vars = use_file_vars
+        self._outdent_re = re.compile(r'^(\t|[ ]{1,%d})' % tab_width, re.M)
+        self.cli = cli
+
+        self._escape_table = g_escape_table.copy()
+        self._code_table = {}
+        if "smarty-pants" in self.extras:
+            self._escape_table['"'] = _hash_text('"')
+            self._escape_table["'"] = _hash_text("'")
+
+    def reset(self):
+        self.urls = {}
+        self.titles = {}
+        self.html_blocks = {}
+        self.html_spans = {}
+        self.list_level = 0
+        self.extras = self._instance_extras.copy()
+        self._setup_extras()
+        self._toc = None
+
+    def _setup_extras(self):
+        if "footnotes" in self.extras:
+            # order of insertion matters for footnotes. Use ordered dict for Python < 3.7
+            # https://docs.python.org/3/whatsnew/3.7.html#summary-release-highlights
+            self.footnotes = OrderedDict()
+            self.footnote_ids = []
+        if "header-ids" in self.extras:
+            if not hasattr(self, '_count_from_header_id') or self.extras['header-ids'].get('reset-count', False):
+                self._count_from_header_id = defaultdict(int)
+        if "metadata" in self.extras:
+            self.metadata = {}
+
+        self.extra_classes = {}
+        for name, klass in Extra._registry.items():
+            if name not in self.extras:
+                #print(name, "not in", self.extras)
+                continue
+            self.extra_classes[name] = klass(self, (self.extras.get(name, {})))
+
+    # Per <https://developer.mozilla.org/en-US/docs/HTML/Element/a> "rel"
+    # should only be used in <a> tags with an "href" attribute.
+
+    # Opens the linked document in a new window or tab
+    # should only used in <a> tags with an "href" attribute.
+    # same with _a_nofollow
+    _a_nofollow_or_blank_links = re.compile(r"""
+        <(a)
+        (
+            [^>]*
+            href=   # href is required
+            ['"]?   # HTML5 attribute values do not have to be quoted
+            [^#'"]  # We don't want to match href values that start with # (like footnotes)
+        )
+        """,
+        re.IGNORECASE | re.VERBOSE
+    )
+
+    def convert(self, text):
+        """Convert the given text."""
+        # Main function. The order in which other subs are called here is
+        # essential. Link and image substitutions need to happen before
+        # _EscapeSpecialChars(), so that any *'s or _'s in the <a>
+        # and <img> tags get encoded.
+
+        # Clear the global hashes. If we don't clear these, you get conflicts
+        # from other articles when generating a page which contains more than
+        # one article (e.g. an index page that shows the N most recent
+        # articles):
+        self.reset()
+
+        if not isinstance(text, str):
+            # TODO: perhaps shouldn't presume UTF-8 for string input?
+            text = str(text, 'utf-8')
+
+        if self.use_file_vars:
+            # Look for emacs-style file variable hints.
+            text = self._emacs_oneliner_vars_pat.sub(self._emacs_vars_oneliner_sub, text)
+            emacs_vars = self._get_emacs_vars(text)
+            if "markdown-extras" in emacs_vars:
+                splitter = re.compile("[ ,]+")
+                for e in splitter.split(emacs_vars["markdown-extras"]):
+                    if '=' in e:
+                        ename, earg = e.split('=', 1)
+                        try:
+                            earg = int(earg)
+                        except ValueError:
+                            pass
+                    else:
+                        ename, earg = e, None
+                    self.extras[ename] = earg
+
+            self._setup_extras()
+
+        # Standardize line endings:
+        text = text.replace("\r\n", "\n")
+        text = text.replace("\r", "\n")
+
+        # Make sure $text ends with a couple of newlines:
+        text += "\n\n"
+
+        # Convert all tabs to spaces.
+        text = self._detab(text)
+
+        # Strip any lines consisting only of spaces and tabs.
+        # This makes subsequent regexen easier to write, because we can
+        # match consecutive blank lines with /\n+/ instead of something
+        # contorted like /[ \t]*\n+/ .
+        text = self._ws_only_line_re.sub("", text)
+
+        # strip metadata from head and extract
+        if "metadata" in self.extras:
+            text = self._extract_metadata(text)
+
+        text = self.preprocess(text)
+
+        if self.safe_mode:
+            text = self._hash_html_spans(text)
+
+        # Turn block-level HTML blocks into hash entries
+        text = self._hash_html_blocks(text, raw=True)
+
+        # Strip link definitions, store in hashes.
+        if "footnotes" in self.extras:
+            # Must do footnotes first because an unlucky footnote defn
+            # looks like a link defn:
+            #   [^4]: this "looks like a link defn"
+            text = self._strip_footnote_definitions(text)
+        text = self._strip_link_definitions(text)
+
+        text = self._run_block_gamut(text)
+
+        if "footnotes" in self.extras:
+            text = self._add_footnotes(text)
+
+        text = self.postprocess(text)
+
+        text = self._unescape_special_chars(text)
+
+        if self.safe_mode:
+            text = self._unhash_html_spans(text)
+            # return the removed text warning to its markdown.py compatible form
+            text = text.replace(self.html_removed_text, self.html_removed_text_compat)
+
+        do_target_blank_links = "target-blank-links" in self.extras
+        do_nofollow_links = "nofollow" in self.extras
+
+        if do_target_blank_links and do_nofollow_links:
+            text = self._a_nofollow_or_blank_links.sub(r'<\1 rel="nofollow noopener" target="_blank"\2', text)
+        elif do_target_blank_links:
+            text = self._a_nofollow_or_blank_links.sub(r'<\1 rel="noopener" target="_blank"\2', text)
+        elif do_nofollow_links:
+            text = self._a_nofollow_or_blank_links.sub(r'<\1 rel="nofollow"\2', text)
+
+        if "toc" in self.extras and self._toc:
+            if self.extras['header-ids'].get('mixed'):
+                # TOC will only be out of order if mixed headers is enabled
+                def toc_sort(entry):
+                    '''Sort the TOC by order of appearance in text'''
+                    return re.search(
+                        # header tag, any attrs, the ID, any attrs, the text, close tag
+                        r'^<(h%d).*?id=(["\'])%s\2.*>%s</\1>$' % (entry[0], entry[1], re.escape(entry[2])),
+                        text, re.M
+                    ).start()
+
+                self._toc.sort(key=toc_sort)
+            self._toc_html = calculate_toc_html(self._toc)
+
+            # Prepend toc html to output
+            if self.cli or (self.extras['toc'] is not None and self.extras['toc'].get('prepend', False)):
+                text = '{}\n{}'.format(self._toc_html, text)
+
+        text += "\n"
+
+        # Attach attrs to output
+        rv = UnicodeWithAttrs(text)
+
+        if "toc" in self.extras and self._toc:
+            rv.toc_html = self._toc_html
+
+        if "metadata" in self.extras:
+            rv.metadata = self.metadata
+        return rv
+
+    @mark_stage(Stage.POSTPROCESS)
+    def postprocess(self, text):
+        """A hook for subclasses to do some postprocessing of the html, if
+        desired. This is called before unescaping of special chars and
+        unhashing of raw HTML spans.
+        """
+        return text
+
+    @mark_stage(Stage.PREPROCESS)
+    def preprocess(self, text):
+        """A hook for subclasses to do some preprocessing of the Markdown, if
+        desired. This is called after basic formatting of the text, but prior
+        to any extras, safe mode, etc. processing.
+        """
+        return text
+
+    # Is metadata if the content starts with optional '---'-fenced `key: value`
+    # pairs. E.g. (indented for presentation):
+    #   ---
+    #   foo: bar
+    #   another-var: blah blah
+    #   ---
+    #   # header
+    # or:
+    #   foo: bar
+    #   another-var: blah blah
+    #
+    #   # header
+    _meta_data_pattern = re.compile(r'''
+        ^{0}(  # optional opening fence
+            (?:
+                {1}:(?:\n+[ \t]+.*)+  # indented lists
+            )|(?:
+                (?:{1}:\s+>(?:\n\s+.*)+?)  # multiline long descriptions
+                (?=\n{1}:\s*.*\n|\s*\Z)  # match up until the start of the next key:value definition or the end of the input text
+            )|(?:
+                {1}:(?! >).*\n?  # simple key:value pair, leading spaces allowed
+            )
+        ){0}  # optional closing fence
+        '''.format(r'(?:---[\ \t]*\n)?', r'[\S \t]*\w[\S \t]*\s*'), re.MULTILINE | re.VERBOSE
+    )
+
+    _key_val_list_pat = re.compile(
+        r"^-(?:[ \t]*([^\n]*)(?:[ \t]*[:-][ \t]*(\S+))?)(?:\n((?:[ \t]+[^\n]+\n?)+))?",
+        re.MULTILINE,
+    )
+    _key_val_dict_pat = re.compile(
+        r"^([^:\n]+)[ \t]*:[ \t]*([^\n]*)(?:((?:\n[ \t]+[^\n]+)+))?", re.MULTILINE
+    )  # grp0: key, grp1: value, grp2: multiline value
+    _meta_data_fence_pattern = re.compile(r'^---[\ \t]*\n', re.MULTILINE)
+    _meta_data_newline = re.compile("^\n", re.MULTILINE)
+
+    def _extract_metadata(self, text):
+        if text.startswith("---"):
+            fence_splits = re.split(self._meta_data_fence_pattern, text, maxsplit=2)
+            metadata_content = fence_splits[1]
+            match = re.findall(self._meta_data_pattern, metadata_content)
+            if not match:
+                return text
+            tail = fence_splits[2]
+        else:
+            metadata_split = re.split(self._meta_data_newline, text, maxsplit=1)
+            metadata_content = metadata_split[0]
+            match = re.findall(self._meta_data_pattern, metadata_content)
+            if not match:
+                return text
+            tail = metadata_split[1]
+
+        def parse_structured_value(value):
+            vs = value.lstrip()
+            vs = value.replace(v[: len(value) - len(vs)], "\n")[1:]
+
+            # List
+            if vs.startswith("-"):
+                r = []
+                for match in re.findall(self._key_val_list_pat, vs):
+                    if match[0] and not match[1] and not match[2]:
+                        r.append(match[0].strip())
+                    elif match[0] == ">" and not match[1] and match[2]:
+                        r.append(match[2].strip())
+                    elif match[0] and match[1]:
+                        r.append({match[0].strip(): match[1].strip()})
+                    elif not match[0] and not match[1] and match[2]:
+                        r.append(parse_structured_value(match[2]))
+                    else:
+                        # Broken case
+                        pass
+
+                return r
+
+            # Dict
+            else:
+                return {
+                    match[0].strip(): (
+                        match[1].strip()
+                        if match[1]
+                        else parse_structured_value(match[2])
+                    )
+                    for match in re.findall(self._key_val_dict_pat, vs)
+                }
+
+        for item in match:
+
+            k, v = item.split(":", 1)
+
+            # Multiline value
+            if v[:3] == " >\n":
+                self.metadata[k.strip()] = _dedent(v[3:]).strip()
+
+            # Empty value
+            elif v == "\n":
+                self.metadata[k.strip()] = ""
+
+            # Structured value
+            elif v[0] == "\n":
+                self.metadata[k.strip()] = parse_structured_value(v)
+
+            # Simple value
+            else:
+                self.metadata[k.strip()] = v.strip()
+
+        return tail
+
+    _emacs_oneliner_vars_pat = re.compile(r"((?:<!--)?\s*-\*-)\s*(?:(\S[^\r\n]*?)([\r\n]\s*)?)?(-\*-\s*(?:-->)?)", re.UNICODE)
+    # This regular expression is intended to match blocks like this:
+    #    PREFIX Local Variables: SUFFIX
+    #    PREFIX mode: Tcl SUFFIX
+    #    PREFIX End: SUFFIX
+    # Some notes:
+    # - "[ \t]" is used instead of "\s" to specifically exclude newlines
+    # - "(\r\n|\n|\r)" is used instead of "$" because the sre engine does
+    #   not like anything other than Unix-style line terminators.
+    _emacs_local_vars_pat = re.compile(r"""^
+        (?P<prefix>(?:[^\r\n|\n|\r])*?)
+        [\ \t]*Local\ Variables:[\ \t]*
+        (?P<suffix>.*?)(?:\r\n|\n|\r)
+        (?P<content>.*?\1End:)
+        """, re.IGNORECASE | re.MULTILINE | re.DOTALL | re.VERBOSE)
+
+    def _emacs_vars_oneliner_sub(self, match):
+        if match.group(1).strip() == '-*-' and match.group(4).strip() == '-*-':
+            lead_ws = re.findall(r'^\s*', match.group(1))[0]
+            tail_ws = re.findall(r'\s*$', match.group(4))[0]
+            return '%s<!-- %s %s %s -->%s' % (lead_ws, '-*-', match.group(2).strip(), '-*-', tail_ws)
+
+        start, end = match.span()
+        return match.string[start: end]
+
+    def _get_emacs_vars(self, text):
+        """Return a dictionary of emacs-style local variables.
+
+        Parsing is done loosely according to this spec (and according to
+        some in-practice deviations from this):
+        http://www.gnu.org/software/emacs/manual/html_node/emacs/Specifying-File-Variables.html#Specifying-File-Variables
+        """
+        emacs_vars = {}
+        SIZE = pow(2, 13)  # 8kB
+
+        # Search near the start for a '-*-'-style one-liner of variables.
+        head = text[:SIZE]
+        if "-*-" in head:
+            match = self._emacs_oneliner_vars_pat.search(head)
+            if match:
+                emacs_vars_str = match.group(2)
+                assert '\n' not in emacs_vars_str
+                emacs_var_strs = [s.strip() for s in emacs_vars_str.split(';')
+                                  if s.strip()]
+                if len(emacs_var_strs) == 1 and ':' not in emacs_var_strs[0]:
+                    # While not in the spec, this form is allowed by emacs:
+                    #   -*- Tcl -*-
+                    # where the implied "variable" is "mode". This form
+                    # is only allowed if there are no other variables.
+                    emacs_vars["mode"] = emacs_var_strs[0].strip()
+                else:
+                    for emacs_var_str in emacs_var_strs:
+                        try:
+                            variable, value = emacs_var_str.strip().split(':', 1)
+                        except ValueError:
+                            log.debug("emacs variables error: malformed -*- "
+                                      "line: %r", emacs_var_str)
+                            continue
+                        # Lowercase the variable name because Emacs allows "Mode"
+                        # or "mode" or "MoDe", etc.
+                        emacs_vars[variable.lower()] = value.strip()
+
+        tail = text[-SIZE:]
+        if "Local Variables" in tail:
+            match = self._emacs_local_vars_pat.search(tail)
+            if match:
+                prefix = match.group("prefix")
+                suffix = match.group("suffix")
+                lines = match.group("content").splitlines(0)
+                # print "prefix=%r, suffix=%r, content=%r, lines: %s"\
+                #      % (prefix, suffix, match.group("content"), lines)
+
+                # Validate the Local Variables block: proper prefix and suffix
+                # usage.
+                for i, line in enumerate(lines):
+                    if not line.startswith(prefix):
+                        log.debug("emacs variables error: line '%s' "
+                                  "does not use proper prefix '%s'"
+                                  % (line, prefix))
+                        return {}
+                    # Don't validate suffix on last line. Emacs doesn't care,
+                    # neither should we.
+                    if i != len(lines)-1 and not line.endswith(suffix):
+                        log.debug("emacs variables error: line '%s' "
+                                  "does not use proper suffix '%s'"
+                                  % (line, suffix))
+                        return {}
+
+                # Parse out one emacs var per line.
+                continued_for = None
+                for line in lines[:-1]:  # no var on the last line ("PREFIX End:")
+                    if prefix: line = line[len(prefix):]  # strip prefix
+                    if suffix: line = line[:-len(suffix)]  # strip suffix
+                    line = line.strip()
+                    if continued_for:
+                        variable = continued_for
+                        if line.endswith('\\'):
+                            line = line[:-1].rstrip()
+                        else:
+                            continued_for = None
+                        emacs_vars[variable] += ' ' + line
+                    else:
+                        try:
+                            variable, value = line.split(':', 1)
+                        except ValueError:
+                            log.debug("local variables error: missing colon "
+                                      "in local variables entry: '%s'" % line)
+                            continue
+                        # Do NOT lowercase the variable name, because Emacs only
+                        # allows "mode" (and not "Mode", "MoDe", etc.) in this block.
+                        value = value.strip()
+                        if value.endswith('\\'):
+                            value = value[:-1].rstrip()
+                            continued_for = variable
+                        else:
+                            continued_for = None
+                        emacs_vars[variable] = value
+
+        # Unquote values.
+        for var, val in list(emacs_vars.items()):
+            if len(val) > 1 and (val.startswith('"') and val.endswith('"')
+               or val.startswith('"') and val.endswith('"')):
+                emacs_vars[var] = val[1:-1]
+
+        return emacs_vars
+
+    def _detab_line(self, line):
+        r"""Recusively convert tabs to spaces in a single line.
+
+        Called from _detab()."""
+        if '\t' not in line:
+            return line
+        chunk1, chunk2 = line.split('\t', 1)
+        chunk1 += (' ' * (self.tab_width - len(chunk1) % self.tab_width))
+        output = chunk1 + chunk2
+        return self._detab_line(output)
+
+    def _detab(self, text):
+        r"""Iterate text line by line and convert tabs to spaces.
+
+            >>> m = Markdown()
+            >>> m._detab("\tfoo")
+            '    foo'
+            >>> m._detab("  \tfoo")
+            '    foo'
+            >>> m._detab("\t  foo")
+            '      foo'
+            >>> m._detab("  foo")
+            '  foo'
+            >>> m._detab("  foo\n\tbar\tblam")
+            '  foo\n    bar blam'
+        """
+        if '\t' not in text:
+            return text
+        output = []
+        for line in text.splitlines():
+            output.append(self._detab_line(line))
+        return '\n'.join(output)
+
+    # I broke out the html5 tags here and add them to _block_tags_a and
+    # _block_tags_b.  This way html5 tags are easy to keep track of.
+    _html5tags = '|article|aside|header|hgroup|footer|nav|section|figure|figcaption'
+
+    _block_tags_a = 'p|div|h[1-6]|blockquote|pre|table|dl|ol|ul|script|noscript|form|fieldset|iframe|math|ins|del|style'
+    _block_tags_a += _html5tags
+
+    _strict_tag_block_re = re.compile(r"""
+        (                       # save in \1
+            ^                   # start of line  (with re.M)
+            <(%s)               # start tag = \2
+            \b                  # word break
+            (.*\n)*?            # any number of lines, minimally matching
+            </\2>               # the matching end tag
+            [ \t]*              # trailing spaces/tabs
+            (?=\n+|\Z)          # followed by a newline or end of document
+        )
+        """ % _block_tags_a,
+        re.X | re.M)
+
+    _block_tags_b = 'p|div|h[1-6]|blockquote|pre|table|dl|ol|ul|script|noscript|form|fieldset|iframe|math'
+    _block_tags_b += _html5tags
+
+    _span_tags = (
+        'a|abbr|acronym|b|bdo|big|br|button|cite|code|dfn|em|i|img|input|kbd|label|map|object|output|q'
+        '|samp|script|select|small|span|strong|sub|sup|textarea|time|tt|var'
+    )
+
+    _liberal_tag_block_re = re.compile(r"""
+        (                       # save in \1
+            ^                   # start of line  (with re.M)
+            <(%s)               # start tag = \2
+            \b                  # word break
+            (.*\n)*?            # any number of lines, minimally matching
+            .*</\2>             # the matching end tag
+            [ \t]*              # trailing spaces/tabs
+            (?=\n+|\Z)          # followed by a newline or end of document
+        )
+        """ % _block_tags_b,
+        re.X | re.M)
+
+    _html_markdown_attr_re = re.compile(
+        r'''\s+markdown=("1"|'1')''')
+    def _hash_html_block_sub(self, match, raw=False):
+        if isinstance(match, str):
+            html = match
+            tag = None
+        else:
+            html = match.group(1)
+            try:
+                tag = match.group(2)
+            except IndexError:
+                tag = None
+
+        tag = tag or re.match(r'.*?<(\S).*?>', html).group(1)
+
+        if raw and self.safe_mode:
+            html = self._sanitize_html(html)
+        elif 'markdown-in-html' in self.extras and 'markdown=' in html:
+            first_line = html.split('\n', 1)[0]
+            m = self._html_markdown_attr_re.search(first_line)
+            if m:
+                lines = html.split('\n')
+                # if MD is on same line as opening tag then split across two lines
+                lines = list(filter(None, (re.split(r'(.*?<%s.*markdown=.*?>)' % tag, lines[0])))) + lines[1:]
+                # if MD on same line as closing tag, split across two lines
+                lines = lines[:-1] + list(filter(None, re.split(r'(\s*?</%s>.*?$)' % tag, lines[-1])))
+                # extract key sections of the match
+                first_line = lines[0]
+                middle = '\n'.join(lines[1:-1])
+                last_line = lines[-1]
+                # remove `markdown="1"` attr from tag
+                first_line = first_line[:m.start()] + first_line[m.end():]
+                # hash the HTML segments to protect them
+                f_key = _hash_text(first_line)
+                self.html_blocks[f_key] = first_line
+                l_key = _hash_text(last_line)
+                self.html_blocks[l_key] = last_line
+                return ''.join(["\n\n", f_key,
+                    "\n\n", middle, "\n\n",
+                    l_key, "\n\n"])
+        elif self.extras.get('header-ids', {}).get('mixed') and self._h_tag_re.match(html):
+            html = self._h_tag_re.sub(self._h_tag_sub, html)
+        key = _hash_text(html)
+        self.html_blocks[key] = html
+        return "\n\n" + key + "\n\n"
+
+    @mark_stage(Stage.HASH_HTML)
+    def _hash_html_blocks(self, text, raw=False):
+        """Hashify HTML blocks
+
+        We only want to do this for block-level HTML tags, such as headers,
+        lists, and tables. That's because we still want to wrap <p>s around
+        "paragraphs" that are wrapped in non-block-level tags, such as anchors,
+        phrase emphasis, and spans. The list of tags we're looking for is
+        hard-coded.
+
+        @param raw {boolean} indicates if these are raw HTML blocks in
+            the original source. It makes a difference in "safe" mode.
+        """
+        if '<' not in text:
+            return text
+
+        # Pass `raw` value into our calls to self._hash_html_block_sub.
+        hash_html_block_sub = _curry(self._hash_html_block_sub, raw=raw)
+
+        # First, look for nested blocks, e.g.:
+        #   <div>
+        #       <div>
+        #       tags for inner block must be indented.
+        #       </div>
+        #   </div>
+        #
+        # The outermost tags must start at the left margin for this to match, and
+        # the inner nested divs must be indented.
+        # We need to do this before the next, more liberal match, because the next
+        # match will start at the first `<div>` and stop at the first `</div>`.
+        text = self._strict_tag_block_sub(text, self._block_tags_a, hash_html_block_sub)
+
+        # Now match more liberally, simply from `\n<tag>` to `</tag>\n`
+        text = self._liberal_tag_block_re.sub(hash_html_block_sub, text)
+
+        # now do the same for spans that are acting like blocks
+        # eg: an anchor split over multiple lines for readability
+        text = self._strict_tag_block_sub(
+            text, self._span_tags,
+            # inline elements can't contain block level elements, so only span gamut is required
+            lambda t: hash_html_block_sub(self._run_span_gamut(t))
+        )
+
+        # Special case just for <hr />. It was easier to make a special
+        # case than to make the other regex more complicated.
+        if "<hr" in text:
+            _hr_tag_re = _hr_tag_re_from_tab_width(self.tab_width)
+            text = _hr_tag_re.sub(hash_html_block_sub, text)
+
+        # Special case for standalone HTML comments:
+        if "<!--" in text:
+            start = 0
+            while True:
+                # Delimiters for next comment block.
+                try:
+                    start_idx = text.index("<!--", start)
+                except ValueError:
+                    break
+                try:
+                    end_idx = text.index("-->", start_idx) + 3
+                except ValueError:
+                    break
+
+                # Start position for next comment block search.
+                start = end_idx
+
+                # Validate whitespace before comment.
+                if start_idx:
+                    # - Up to `tab_width - 1` spaces before start_idx.
+                    for i in range(self.tab_width - 1):
+                        if text[start_idx - 1] != ' ':
+                            break
+                        start_idx -= 1
+                        if start_idx == 0:
+                            break
+                    # - Must be preceded by 2 newlines or hit the start of
+                    #   the document.
+                    if start_idx == 0:
+                        pass
+                    elif start_idx == 1 and text[0] == '\n':
+                        start_idx = 0  # to match minute detail of Markdown.pl regex
+                    elif text[start_idx-2:start_idx] == '\n\n':
+                        pass
+                    else:
+                        break
+
+                # Validate whitespace after comment.
+                # - Any number of spaces and tabs.
+                while end_idx < len(text):
+                    if text[end_idx] not in ' \t':
+                        break
+                    end_idx += 1
+                # - Must be following by 2 newlines or hit end of text.
+                if text[end_idx:end_idx+2] not in ('', '\n', '\n\n'):
+                    continue
+
+                # Escape and hash (must match `_hash_html_block_sub`).
+                html = text[start_idx:end_idx]
+                if raw and self.safe_mode:
+                    html = self._sanitize_html(html)
+                key = _hash_text(html)
+                self.html_blocks[key] = html
+                text = text[:start_idx] + "\n\n" + key + "\n\n" + text[end_idx:]
+
+        if "xml" in self.extras:
+            # Treat XML processing instructions and namespaced one-liner
+            # tags as if they were block HTML tags. E.g., if standalone
+            # (i.e. are their own paragraph), the following do not get
+            # wrapped in a <p> tag:
+            #    <?foo bar?>
+            #
+            #    <xi:include xmlns:xi="http://www.w3.org/2001/XInclude" href="chapter_1.md"/>
+            _xml_oneliner_re = _xml_oneliner_re_from_tab_width(self.tab_width)
+            text = _xml_oneliner_re.sub(hash_html_block_sub, text)
+
+        return text
+
+    def _strict_tag_block_sub(self, text, html_tags_re, callback, allow_indent=False):
+        '''
+        Finds and substitutes HTML blocks within blocks of text
+
+        Args:
+            text: the text to search
+            html_tags_re: a regex pattern of HTML block tags to match against.
+                For example, `Markdown._block_tags_a`
+            callback: callback function that receives the found HTML text block
+            allow_indent: allow matching HTML blocks that are not completely outdented
+        '''
+        tag_count = 0
+        current_tag = html_tags_re
+        block = ''
+        result = ''
+
+        for chunk in text.splitlines(True):
+            is_markup = re.match(
+                r'^(\s{0,%s})(?:</code>(?=</pre>))?(</?(%s)\b>?)' % ('' if allow_indent else '0', current_tag), chunk
+            )
+            block += chunk
+
+            if is_markup:
+                if chunk.startswith('%s</' % is_markup.group(1)):
+                    tag_count -= 1
+                else:
+                    # if close tag is in same line
+                    if self._tag_is_closed(is_markup.group(3), chunk):
+                        # we must ignore these
+                        is_markup = None
+                    else:
+                        tag_count += 1
+                        current_tag = is_markup.group(3)
+
+            if tag_count == 0:
+                if is_markup:
+                    block = callback(block.rstrip('\n'))  # remove trailing newline
+                current_tag = html_tags_re
+                result += block
+                block = ''
+
+        result += block
+
+        return result
+
+    def _tag_is_closed(self, tag_name, text):
+        # super basic check if number of open tags == number of closing tags
+        return len(re.findall('<%s(?:.*?)>' % tag_name, text)) == len(re.findall('</%s>' % tag_name, text))
+
+    @mark_stage(Stage.LINK_DEFS)
+    def _strip_link_definitions(self, text):
+        # Strips link definitions from text, stores the URLs and titles in
+        # hash references.
+        less_than_tab = self.tab_width - 1
+
+        # Link defs are in the form:
+        #   [id]: url "optional title"
+        _link_def_re = re.compile(r"""
+            ^[ ]{0,%d}\[(.+)\]: # id = \1
+              [ \t]*
+              \n?               # maybe *one* newline
+              [ \t]*
+            <?(.+?)>?           # url = \2
+              [ \t]*
+            (?:
+                \n?             # maybe one newline
+                [ \t]*
+                (?<=\s)         # lookbehind for whitespace
+                ['"(]
+                ([^\n]*)        # title = \3
+                ['")]
+                [ \t]*
+            )?  # title is optional
+            (?:\n+|\Z)
+            """ % less_than_tab, re.X | re.M | re.U)
+        return _link_def_re.sub(self._extract_link_def_sub, text)
+
+    def _extract_link_def_sub(self, match):
+        id, url, title = match.groups()
+        key = id.lower()    # Link IDs are case-insensitive
+        self.urls[key] = self._encode_amps_and_angles(url)
+        if title:
+            self.titles[key] = title
+        return ""
+
+    def _extract_footnote_def_sub(self, match):
+        id, text = match.groups()
+        text = _dedent(text, skip_first_line=not text.startswith('\n')).strip()
+        normed_id = re.sub(r'\W', '-', id)
+        # Ensure footnote text ends with a couple newlines (for some
+        # block gamut matches).
+        self.footnotes[normed_id] = text + "\n\n"
+        return ""
+
+    def _strip_footnote_definitions(self, text):
+        """A footnote definition looks like this:
+
+            [^note-id]: Text of the note.
+
+                May include one or more indented paragraphs.
+
+        Where,
+        - The 'note-id' can be pretty much anything, though typically it
+          is the number of the footnote.
+        - The first paragraph may start on the next line, like so:
+
+            [^note-id]:
+                Text of the note.
+        """
+        less_than_tab = self.tab_width - 1
+        footnote_def_re = re.compile(r'''
+            ^[ ]{0,%d}\[\^(.+)\]:   # id = \1
+            [ \t]*
+            (                       # footnote text = \2
+              # First line need not start with the spaces.
+              (?:\s*.*\n+)
+              (?:
+                (?:[ ]{%d} | \t)  # Subsequent lines must be indented.
+                .*\n+
+              )*
+            )
+            # Lookahead for non-space at line-start, or end of doc.
+            (?:(?=^[ ]{0,%d}\S)|\Z)
+            ''' % (less_than_tab, self.tab_width, self.tab_width),
+            re.X | re.M)
+        return footnote_def_re.sub(self._extract_footnote_def_sub, text)
+
+    _hr_re = re.compile(r'^[ ]{0,3}([-_*])[ ]{0,2}(\1[ ]{0,2}){2,}$', re.M)
+
+    @mark_stage(Stage.BLOCK_GAMUT)
+    def _run_block_gamut(self, text):
+        # These are all the transformations that form block-level
+        # tags like paragraphs, headers, and list items.
+
+        text = self._do_headers(text)
+
+        # Do Horizontal Rules:
+        # On the number of spaces in horizontal rules: The spec is fuzzy: "If
+        # you wish, you may use spaces between the hyphens or asterisks."
+        # Markdown.pl 1.0.1's hr regexes limit the number of spaces between the
+        # hr chars to one or two. We'll reproduce that limit here.
+        hr = "\n<hr"+self.empty_element_suffix+"\n"
+        text = re.sub(self._hr_re, hr, text)
+
+        text = self._do_lists(text)
+
+        text = self._do_code_blocks(text)
+
+        text = self._do_block_quotes(text)
+
+        # We already ran _HashHTMLBlocks() before, in Markdown(), but that
+        # was to escape raw HTML in the original Markdown source. This time,
+        # we're escaping the markup we've just created, so that we don't wrap
+        # <p> tags around block-level tags.
+        text = self._hash_html_blocks(text)
+
+        text = self._form_paragraphs(text)
+
+        return text
+
+    @mark_stage(Stage.SPAN_GAMUT)
+    def _run_span_gamut(self, text):
+        # These are all the transformations that occur *within* block-level
+        # tags like paragraphs, headers, and list items.
+
+        text = self._do_code_spans(text)
+
+        text = self._escape_special_chars(text)
+
+        # Process anchor and image tags.
+        text = self._do_links(text)
+
+        # Make links out of things like `<http://example.com/>`
+        # Must come after _do_links(), because you can use < and >
+        # delimiters in inline links like [this](<url>).
+        text = self._do_auto_links(text)
+
+        text = self._encode_amps_and_angles(text)
+
+        text = self._do_italics_and_bold(text)
+
+        # Do hard breaks
+        text = re.sub(r" {2,}\n(?!\<(?:\/?(ul|ol|li))\>)", "<br%s\n" % self.empty_element_suffix, text)
+
+        return text
+
+    # "Sorta" because auto-links are identified as "tag" tokens.
+    _sorta_html_tokenize_re = re.compile(r"""
+        (
+            \\*  # escapes
+            (?:
+                # tag
+                </?
+                (?:\w+)                                     # tag name
+                (?:\s+(?:[\w-]+:)?[\w-]+=(?:".*?"|'.*?'))*  # attributes
+                \s*/?>
+                |
+                # auto-link (e.g., <http://www.activestate.com/>)
+                <[\w~:/?#\[\]@!$&'\(\)*+,;%=\.\\-]+>
+                |
+                <!--.*?-->      # comment
+                |
+                <\?.*?\?>       # processing instruction
+            )
+        )
+        """, re.X)
+
+    @mark_stage(Stage.ESCAPE_SPECIAL)
+    def _escape_special_chars(self, text):
+        # Python markdown note: the HTML tokenization here differs from
+        # that in Markdown.pl, hence the behaviour for subtle cases can
+        # differ (I believe the tokenizer here does a better job because
+        # it isn't susceptible to unmatched '<' and '>' in HTML tags).
+        # Note, however, that '>' is not allowed in an auto-link URL
+        # here.
+        lead_escape_re = re.compile(r'^((?:\\\\)*(?!\\))')
+        escaped = []
+        is_html_markup = False
+        for token in self._sorta_html_tokenize_re.split(text):
+            # check token is preceded by 0 or more PAIRS of escapes, because escape pairs
+            # escape themselves and don't affect the token
+            if is_html_markup and lead_escape_re.match(token):
+                # Within tags/HTML-comments/auto-links, encode * and _
+                # so they don't conflict with their use in Markdown for
+                # italics and strong.  We're replacing each such
+                # character with its corresponding MD5 checksum value;
+                # this is likely overkill, but it should prevent us from
+                # colliding with the escape values by accident.
+                escape_seq, token = lead_escape_re.split(token)[1:] or ('', token)
+                escaped.append(
+                    escape_seq.replace('\\\\', self._escape_table['\\'])
+                    + token.replace('*', self._escape_table['*'])
+                           .replace('_', self._escape_table['_'])
+                )
+            else:
+                escaped.append(self._encode_backslash_escapes(token.replace('\\<', '&lt;')))
+            is_html_markup = not is_html_markup
+        return ''.join(escaped)
+
+    @mark_stage(Stage.HASH_HTML)
+    def _hash_html_spans(self, text):
+        # Used for safe_mode.
+
+        def _is_auto_link(s):
+            if ':' in s and self._auto_link_re.match(s):
+                return True
+            elif '@' in s and self._auto_email_link_re.match(s):
+                return True
+            return False
+
+        def _is_code_span(index, token):
+            try:
+                if token == '<code>':
+                    peek_tokens = split_tokens[index: index + 3]
+                elif token == '</code>':
+                    peek_tokens = split_tokens[index - 2: index + 1]
+                else:
+                    return False
+            except IndexError:
+                return False
+
+            return re.match(r'<code>md5-[A-Fa-f0-9]{32}</code>', ''.join(peek_tokens))
+
+        def _is_comment(token):
+            if self.safe_mode == 'replace':
+                # don't bother processing each section of comment in replace mode. Just do the whole thing
+                return
+            return re.match(r'(<!--)(.*)(-->)', token)
+
+        def _hash(token):
+            key = _hash_text(token)
+            self.html_spans[key] = token
+            return key
+
+        tokens = []
+        split_tokens = self._sorta_html_tokenize_re.split(text)
+        is_html_markup = False
+        for index, token in enumerate(split_tokens):
+            if is_html_markup and not _is_auto_link(token) and not _is_code_span(index, token):
+                is_comment = _is_comment(token)
+                if is_comment:
+                    tokens.append(_hash(self._sanitize_html(is_comment.group(1))))
+                    # sanitise but leave comment body intact for further markdown processing
+                    tokens.append(self._sanitize_html(is_comment.group(2)))
+                    tokens.append(_hash(self._sanitize_html(is_comment.group(3))))
+                else:
+                    tokens.append(_hash(self._sanitize_html(token)))
+            else:
+                tokens.append(self._encode_incomplete_tags(token))
+            is_html_markup = not is_html_markup
+        return ''.join(tokens)
+
+    def _unhash_html_spans(self, text):
+        for key, sanitized in list(self.html_spans.items()):
+            text = text.replace(key, sanitized)
+        return text
+
+    def _sanitize_html(self, s):
+        if self.safe_mode == "replace":
+            return self.html_removed_text
+        elif self.safe_mode == "escape":
+            replacements = [
+                ('&', '&amp;'),
+                ('<', '&lt;'),
+                ('>', '&gt;'),
+            ]
+            for before, after in replacements:
+                s = s.replace(before, after)
+            return s
+        else:
+            raise MarkdownError("invalid value for 'safe_mode': %r (must be "
+                                "'escape' or 'replace')" % self.safe_mode)
+
+    _inline_link_title = re.compile(r'''
+            (                   # \1
+              [ \t]+
+              (['"])            # quote char = \2
+              (?P<title>.*?)
+              \2
+            )?                  # title is optional
+          \)$
+        ''', re.X | re.S)
+    _tail_of_reference_link_re = re.compile(r'''
+          # Match tail of: [text][id]
+          [ ]?          # one optional space
+          (?:\n[ ]*)?   # one optional newline followed by spaces
+          \[
+            (?P<id>.*?)
+          \]
+        ''', re.X | re.S)
+
+    _whitespace = re.compile(r'\s*')
+
+    _strip_anglebrackets = re.compile(r'<(.*)>.*')
+
+    def _find_non_whitespace(self, text, start):
+        """Returns the index of the first non-whitespace character in text
+        after (and including) start
+        """
+        match = self._whitespace.match(text, start)
+        return match.end()
+
+    def _find_balanced(self, text, start, open_c, close_c):
+        """Returns the index where the open_c and close_c characters balance
+        out - the same number of open_c and close_c are encountered - or the
+        end of string if it's reached before the balance point is found.
+        """
+        i = start
+        l = len(text)
+        count = 1
+        while count > 0 and i < l:
+            if text[i] == open_c:
+                count += 1
+            elif text[i] == close_c:
+                count -= 1
+            i += 1
+        return i
+
+    def _extract_url_and_title(self, text, start):
+        """Extracts the url and (optional) title from the tail of a link"""
+        # text[start] equals the opening parenthesis
+        idx = self._find_non_whitespace(text, start+1)
+        if idx == len(text):
+            return None, None, None
+        end_idx = idx
+        has_anglebrackets = text[idx] == "<"
+        if has_anglebrackets:
+            end_idx = self._find_balanced(text, end_idx+1, "<", ">")
+        end_idx = self._find_balanced(text, end_idx, "(", ")")
+        match = self._inline_link_title.search(text, idx, end_idx)
+        if not match:
+            return None, None, None
+        url, title = text[idx:match.start()], match.group("title")
+        if has_anglebrackets:
+            url = self._strip_anglebrackets.sub(r'\1', url)
+        return url, title, end_idx
+
+    # https://developer.mozilla.org/en-US/docs/web/http/basics_of_http/data_urls
+    # https://developer.mozilla.org/en-US/docs/Web/HTTP/Basics_of_HTTP/MIME_types
+    _data_url_re = re.compile(r'''
+        data:
+        # in format type/subtype;parameter=optional
+        (?P<mime>\w+/[\w+\.-]+(?:;\w+=[\w+\.-]+)?)?
+        # optional base64 token
+        (?P<token>;base64)?
+        ,(?P<data>.*)
+    ''', re.X)
+
+    def _protect_url(self, url):
+        '''
+        Function that passes a URL through `_html_escape_url` to remove any nasty characters,
+        and then hashes the now "safe" URL to prevent other safety mechanisms from tampering
+        with it (eg: escaping "&" in URL parameters)
+        '''
+        data_url = self._data_url_re.match(url)
+        charset = None
+        if data_url is not None:
+            mime = data_url.group('mime') or ''
+            if mime.startswith('image/') and data_url.group('token') == ';base64':
+                charset='base64'
+        url = _html_escape_url(url, safe_mode=self.safe_mode, charset=charset)
+        key = _hash_text(url)
+        self._escape_table[url] = key
+        return key
+
+    _safe_protocols = r'(?:https?|ftp):\/\/|(?:mailto|tel):'
+
+    @property
+    def _safe_href(self):
+        '''
+        _safe_href is adapted from pagedown's Markdown.Sanitizer.js
+        From: https://github.com/StackExchange/pagedown/blob/master/LICENSE.txt
+        Original Showdown code copyright (c) 2007 John Fraser
+        Modifications and bugfixes (c) 2009 Dana Robinson
+        Modifications and bugfixes (c) 2009-2014 Stack Exchange Inc.
+        '''
+        safe = r'-\w'
+        # omitted ['"<>] for XSS reasons
+        less_safe = r'#/\.!#$%&\(\)\+,/:;=\?@\[\]^`\{\}\|~'
+        # dot seperated hostname, optional port number, not followed by protocol seperator
+        domain = r'(?:[%s]+(?:\.[%s]+)*)(?:(?<!tel):\d+/?)?(?![^:/]*:/*)' % (safe, safe)
+        fragment = r'[%s]*' % (safe + less_safe)
+
+        return re.compile(r'^(?:(%s)?(%s)(%s)|(#|\.{,2}/)(%s))$' % (self._safe_protocols, domain, fragment, fragment), re.I)
+
+    @mark_stage(Stage.LINKS)
+    def _do_links(self, text):
+        """Turn Markdown link shortcuts into XHTML <a> and <img> tags.
+
+        This is a combination of Markdown.pl's _DoAnchors() and
+        _DoImages(). They are done together because that simplified the
+        approach. It was necessary to use a different approach than
+        Markdown.pl because of the lack of atomic matching support in
+        Python's regex engine used in $g_nested_brackets.
+        """
+        MAX_LINK_TEXT_SENTINEL = 3000  # markdown2 issue 24
+
+        # `anchor_allowed_pos` is used to support img links inside
+        # anchors, but not anchors inside anchors. An anchor's start
+        # pos must be `>= anchor_allowed_pos`.
+        anchor_allowed_pos = 0
+
+        curr_pos = 0
+        while True:  # Handle the next link.
+            # The next '[' is the start of:
+            # - an inline anchor:   [text](url "title")
+            # - a reference anchor: [text][id]
+            # - an inline img:      ![text](url "title")
+            # - a reference img:    ![text][id]
+            # - a footnote ref:     [^id]
+            #   (Only if 'footnotes' extra enabled)
+            # - a footnote defn:    [^id]: ...
+            #   (Only if 'footnotes' extra enabled) These have already
+            #   been stripped in _strip_footnote_definitions() so no
+            #   need to watch for them.
+            # - a link definition:  [id]: url "title"
+            #   These have already been stripped in
+            #   _strip_link_definitions() so no need to watch for them.
+            # - not markup:         [...anything else...
+            try:
+                start_idx = text.index('[', curr_pos)
+            except ValueError:
+                break
+            text_length = len(text)
+
+            # Find the matching closing ']'.
+            # Markdown.pl allows *matching* brackets in link text so we
+            # will here too. Markdown.pl *doesn't* currently allow
+            # matching brackets in img alt text -- we'll differ in that
+            # regard.
+            bracket_depth = 0
+            for p in range(start_idx+1, min(start_idx+MAX_LINK_TEXT_SENTINEL,
+                                            text_length)):
+                ch = text[p]
+                if ch == ']':
+                    bracket_depth -= 1
+                    if bracket_depth < 0:
+                        break
+                elif ch == '[':
+                    bracket_depth += 1
+            else:
+                # Closing bracket not found within sentinel length.
+                # This isn't markup.
+                curr_pos = start_idx + 1
+                continue
+            link_text = text[start_idx+1:p]
+
+            # Fix for issue 341 - Injecting XSS into link text
+            if self.safe_mode:
+                link_text = self._hash_html_spans(link_text)
+                link_text = self._unhash_html_spans(link_text)
+
+            # Possibly a footnote ref?
+            if "footnotes" in self.extras and link_text.startswith("^"):
+                normed_id = re.sub(r'\W', '-', link_text[1:])
+                if normed_id in self.footnotes:
+                    self.footnote_ids.append(normed_id)
+                    result = '<sup class="footnote-ref" id="fnref-%s">' \
+                             '<a href="#fn-%s">%s</a></sup>' \
+                             % (normed_id, normed_id, len(self.footnote_ids))
+                    text = text[:start_idx] + result + text[p+1:]
+                else:
+                    # This id isn't defined, leave the markup alone.
+                    curr_pos = p+1
+                continue
+
+            # Now determine what this is by the remainder.
+            p += 1
+
+            # Inline anchor or img?
+            if text[p:p + 1] == '(':  # attempt at perf improvement
+                url, title, url_end_idx = self._extract_url_and_title(text, p)
+                if url is not None:
+                    # Handle an inline anchor or img.
+                    is_img = start_idx > 0 and text[start_idx-1] == "!"
+                    if is_img:
+                        start_idx -= 1
+
+                    # We've got to encode these to avoid conflicting
+                    # with italics/bold.
+                    url = url.replace('*', self._escape_table['*']) \
+                             .replace('_', self._escape_table['_'])
+                    if title:
+                        title_str = ' title="%s"' % (
+                            _xml_escape_attr(title)
+                                .replace('*', self._escape_table['*'])
+                                .replace('_', self._escape_table['_']))
+                    else:
+                        title_str = ''
+                    if is_img:
+                        img_class_str = self._html_class_str_from_tag("img")
+                        result = '<img src="%s" alt="%s"%s%s%s' \
+                            % (self._protect_url(url),
+                               _xml_escape_attr(link_text),
+                               title_str,
+                               img_class_str,
+                               self.empty_element_suffix)
+                        if "smarty-pants" in self.extras:
+                            result = result.replace('"', self._escape_table['"'])
+                        curr_pos = start_idx + len(result)
+                        anchor_allowed_pos = start_idx + len(result)
+                        text = text[:start_idx] + result + text[url_end_idx:]
+                    elif start_idx >= anchor_allowed_pos:
+                        safe_link = self._safe_href.match(url)
+                        if self.safe_mode and not safe_link:
+                            result_head = '<a href="#"%s>' % (title_str)
+                        else:
+                            result_head = '<a href="%s"%s>' % (self._protect_url(url), title_str)
+                        result = '%s%s</a>' % (result_head, link_text)
+                        if "smarty-pants" in self.extras:
+                            result = result.replace('"', self._escape_table['"'])
+                        # <img> allowed from curr_pos on, <a> from
+                        # anchor_allowed_pos on.
+                        curr_pos = start_idx + len(result_head)
+                        anchor_allowed_pos = start_idx + len(result)
+                        text = text[:start_idx] + result + text[url_end_idx:]
+                    else:
+                        # Anchor not allowed here.
+                        curr_pos = start_idx + 1
+                    continue
+
+            # Reference anchor or img?
+            else:
+                match = self._tail_of_reference_link_re.match(text, p)
+                if match:
+                    # Handle a reference-style anchor or img.
+                    is_img = start_idx > 0 and text[start_idx-1] == "!"
+                    if is_img:
+                        start_idx -= 1
+                    link_id = match.group("id").lower()
+                    if not link_id:
+                        link_id = link_text.lower()  # for links like [this][]
+                    if link_id in self.urls:
+                        url = self.urls[link_id]
+                        # We've got to encode these to avoid conflicting
+                        # with italics/bold.
+                        url = url.replace('*', self._escape_table['*']) \
+                                 .replace('_', self._escape_table['_'])
+                        title = self.titles.get(link_id)
+                        if title:
+                            title = _xml_escape_attr(title) \
+                                .replace('*', self._escape_table['*']) \
+                                .replace('_', self._escape_table['_'])
+                            title_str = ' title="%s"' % title
+                        else:
+                            title_str = ''
+                        if is_img:
+                            img_class_str = self._html_class_str_from_tag("img")
+                            result = '<img src="%s" alt="%s"%s%s%s' \
+                                % (self._protect_url(url),
+                                   _xml_escape_attr(link_text),
+                                   title_str,
+                                   img_class_str,
+                                   self.empty_element_suffix)
+                            if "smarty-pants" in self.extras:
+                                result = result.replace('"', self._escape_table['"'])
+                            curr_pos = start_idx + len(result)
+                            text = text[:start_idx] + result + text[match.end():]
+                        elif start_idx >= anchor_allowed_pos:
+                            if self.safe_mode and not self._safe_href.match(url):
+                                result_head = '<a href="#"%s>' % (title_str)
+                            else:
+                                result_head = '<a href="%s"%s>' % (self._protect_url(url), title_str)
+                            result = '%s%s</a>' % (result_head, link_text)
+                            if "smarty-pants" in self.extras:
+                                result = result.replace('"', self._escape_table['"'])
+                            # <img> allowed from curr_pos on, <a> from
+                            # anchor_allowed_pos on.
+                            curr_pos = start_idx + len(result_head)
+                            anchor_allowed_pos = start_idx + len(result)
+                            text = text[:start_idx] + result + text[match.end():]
+                        else:
+                            # Anchor not allowed here.
+                            curr_pos = start_idx + 1
+                    else:
+                        # This id isn't defined, leave the markup alone.
+                        # set current pos to end of link title and continue from there
+                        curr_pos = p
+                    continue
+
+            # Otherwise, it isn't markup.
+            curr_pos = start_idx + 1
+
+        return text
+
+    def header_id_from_text(self, text, prefix, n):
+        """Generate a header id attribute value from the given header
+        HTML content.
+
+        This is only called if the "header-ids" extra is enabled.
+        Subclasses may override this for different header ids.
+
+        @param text {str} The text of the header tag
+        @param prefix {str} The requested prefix for header ids. This is the
+            value of the "header-ids" extra key, if any. Otherwise, None.
+        @param n {int} The <hN> tag number, i.e. `1` for an <h1> tag.
+        @returns {str} The value for the header tag's "id" attribute. Return
+            None to not have an id attribute and to exclude this header from
+            the TOC (if the "toc" extra is specified).
+        """
+        header_id = _slugify(text)
+        if prefix and isinstance(prefix, str):
+            header_id = prefix + '-' + header_id
+
+        self._count_from_header_id[header_id] += 1
+        if 0 == len(header_id) or self._count_from_header_id[header_id] > 1:
+            header_id += '-%s' % self._count_from_header_id[header_id]
+
+        return header_id
+
+    def _header_id_exists(self, text):
+        header_id = _slugify(text)
+        prefix = self.extras['header-ids'].get('prefix')
+        if prefix and isinstance(prefix, str):
+            header_id = prefix + '-' + header_id
+        return header_id in self._count_from_header_id or header_id in map(lambda x: x[1], self._toc)
+
+    def _toc_add_entry(self, level, id, name):
+        if level > self._toc_depth:
+            return
+        if self._toc is None:
+            self._toc = []
+        self._toc.append((level, id, self._unescape_special_chars(name)))
+
+    _h_re_base = r'''
+        (^(.+)[ \t]{0,99}\n(=+|-+)[ \t]*\n+)
+        |
+        (^(\#{1,6})  # \1 = string of #'s
+        [ \t]%s
+        (.+?)       # \2 = Header text
+        [ \t]{0,99}
+        (?<!\\)     # ensure not an escaped trailing '#'
+        \#*         # optional closing #'s (not counted)
+        \n+
+        )
+        '''
+
+    _h_re = re.compile(_h_re_base % '*', re.X | re.M)
+    _h_re_tag_friendly = re.compile(_h_re_base % '+', re.X | re.M)
+
+    def _h_sub(self, match):
+        '''Handles processing markdown headers'''
+        if match.group(1) is not None and match.group(3) == "-":
+            return match.group(1)
+        elif match.group(1) is not None:
+            # Setext header
+            n = {"=": 1, "-": 2}[match.group(3)[0]]
+            header_group = match.group(2)
+        else:
+            # atx header
+            n = len(match.group(5))
+            header_group = match.group(6)
+
+        demote_headers = self.extras.get("demote-headers")
+        if demote_headers:
+            n = min(n + demote_headers, 6)
+        header_id_attr = ""
+        if "header-ids" in self.extras:
+            header_id = self.header_id_from_text(header_group,
+                self.extras["header-ids"].get('prefix'), n)
+            if header_id:
+                header_id_attr = ' id="%s"' % header_id
+        html = self._run_span_gamut(header_group)
+        if "toc" in self.extras and header_id:
+            self._toc_add_entry(n, header_id, html)
+        return "<h%d%s>%s</h%d>\n\n" % (n, header_id_attr, html, n)
+
+    _h_tag_re = re.compile(r'''
+        ^<h([1-6])(.*)>  # \1 tag num, \2 attrs
+        (.*)  # \3 text
+        </h\1>
+    ''', re.X | re.M)
+
+    def _h_tag_sub(self, match):
+        '''Different to `_h_sub` in that this function handles existing HTML headers'''
+        text = match.string[match.start(): match.end()]
+        h_level = int(match.group(1))
+        # extract id= attr from tag, trying to account for regex "misses"
+        id_attr = (re.match(r'.*?id=(\S+)?.*', match.group(2) or '') or '')
+        if id_attr:
+            # if id attr exists, extract that
+            id_attr = id_attr.group(1) or ''
+        id_attr = id_attr.strip('\'" ')
+        h_text = match.group(3)
+
+        # check if header was already processed (ie: was a markdown header rather than HTML)
+        if id_attr and self._header_id_exists(id_attr):
+            return text
+
+        # generate new header id if none existed
+        header_id = id_attr or self.header_id_from_text(h_text, self.extras['header-ids'].get('prefix'), h_level)
+        if "toc" in self.extras:
+            self._toc_add_entry(h_level, header_id, h_text)
+        if header_id and not id_attr:
+            # '<h[digit]' + new ID + '...'
+            return text[:3] + ' id="%s"' % header_id + text[3:]
+        return text
+
+    @mark_stage(Stage.HEADERS)
+    def _do_headers(self, text):
+        # Setext-style headers:
+        #     Header 1
+        #     ========
+        #
+        #     Header 2
+        #     --------
+
+        # atx-style headers:
+        #   # Header 1
+        #   ## Header 2
+        #   ## Header 2 with closing hashes ##
+        #   ...
+        #   ###### Header 6
+
+        if 'tag-friendly' in self.extras:
+            return self._h_re_tag_friendly.sub(self._h_sub, text)
+        return self._h_re.sub(self._h_sub, text)
+
+    _marker_ul_chars = '*+-'
+    _marker_any = r'(?:[%s]|\d+\.)' % _marker_ul_chars
+    _marker_ul = '(?:[%s])' % _marker_ul_chars
+    _marker_ol = r'(?:\d+\.)'
+
+    def _list_sub(self, match):
+        lst = match.group(1)
+        lst_type = match.group(4) in self._marker_ul_chars and "ul" or "ol"
+
+        if lst_type == 'ol' and match.group(4) != '1.':
+            # if list doesn't start at 1 then set the ol start attribute
+            lst_opts = ' start="%s"' % match.group(4)[:-1]
+        else:
+            lst_opts = ''
+
+        lst_opts = lst_opts + self._html_class_str_from_tag(lst_type)
+
+        result = self._process_list_items(lst)
+        if self.list_level:
+            return "<%s%s>\n%s</%s>\n" % (lst_type, lst_opts, result, lst_type)
+        else:
+            return "<%s%s>\n%s</%s>\n\n" % (lst_type, lst_opts, result, lst_type)
+
+    @mark_stage(Stage.LISTS)
+    def _do_lists(self, text):
+        # Form HTML ordered (numbered) and unordered (bulleted) lists.
+
+        # Iterate over each *non-overlapping* list match.
+        pos = 0
+        while True:
+            # Find the *first* hit for either list style (ul or ol). We
+            # match ul and ol separately to avoid adjacent lists of different
+            # types running into each other (see issue #16).
+            hits = []
+            for marker_pat in (self._marker_ul, self._marker_ol):
+                less_than_tab = self.tab_width - 1
+                other_marker_pat = self._marker_ul if marker_pat == self._marker_ol else self._marker_ol
+                whole_list = r'''
+                    (                   # \1 = whole list
+                      (                 # \2
+                        ([ ]{0,%d})     # \3 = the indentation level of the list item marker
+                        (%s)            # \4 = first list item marker
+                        [ \t]+
+                        (?!\ *\4\ )     # '- - - ...' isn't a list. See 'not_quite_a_list' test case.
+                      )
+                      (?:.+?)
+                      (                 # \5
+                          \Z
+                        |
+                          \n{2,}
+                          (?=\S)
+                          (?!           # Negative lookahead for another list item marker
+                            [ \t]*
+                            %s[ \t]+
+                          )
+                        |
+                          \n+
+                          (?=
+                            \3          # lookahead for a different style of list item marker
+                            %s[ \t]+
+                          )
+                      )
+                    )
+                ''' % (less_than_tab, marker_pat, marker_pat, other_marker_pat)
+                if self.list_level:  # sub-list
+                    list_re = re.compile("^"+whole_list, re.X | re.M | re.S)
+                else:
+                    list_re = re.compile(r"(?:(?<=\n\n)|\A\n?)"+whole_list,
+                                         re.X | re.M | re.S)
+                match = list_re.search(text, pos)
+                if match:
+                    hits.append((match.start(), match))
+            if not hits:
+                break
+            hits.sort()
+            match = hits[0][1]
+            start, end = match.span()
+            middle = self._list_sub(match)
+            text = text[:start] + middle + text[end:]
+            pos = start + len(middle)  # start pos for next attempted match
+
+        return text
+
+    _list_item_re = re.compile(r'''
+        (\n)?                   # leading line = \1
+        (^[ \t]*)               # leading whitespace = \2
+        (?P<marker>%s) [ \t]+   # list marker = \3
+        ((?:.+?)                # list item text = \4
+        (\n{1,2}))              # eols = \5
+        (?= \n* (\Z | \2 (?P<next_marker>%s) [ \t]+))
+        ''' % (_marker_any, _marker_any),
+        re.M | re.X | re.S)
+
+    _task_list_item_re = re.compile(r'''
+        (\[[\ xX]\])[ \t]+       # tasklist marker = \1
+        (.*)                   # list item text = \2
+    ''', re.M | re.X | re.S)
+
+    _task_list_warpper_str = r'<input type="checkbox" class="task-list-item-checkbox" %sdisabled> %s'
+
+    def _task_list_item_sub(self, match):
+        marker = match.group(1)
+        item_text = match.group(2)
+        if marker in ['[x]','[X]']:
+                return self._task_list_warpper_str % ('checked ', item_text)
+        elif marker == '[ ]':
+                return self._task_list_warpper_str % ('', item_text)
+
+    _last_li_endswith_two_eols = False
+    def _list_item_sub(self, match):
+        item = match.group(4)
+        leading_line = match.group(1)
+        if leading_line or "\n\n" in item or self._last_li_endswith_two_eols:
+            item = self._uniform_outdent(item, min_outdent=' ', max_outdent=self.tab)[1]
+            item = self._run_block_gamut(item)
+        else:
+            # Recursion for sub-lists:
+            item = self._do_lists(self._uniform_outdent(item, min_outdent=' ')[1])
+            if item.endswith('\n'):
+                item = item[:-1]
+            item = self._run_span_gamut(item)
+        self._last_li_endswith_two_eols = (len(match.group(5)) == 2)
+
+        if "task_list" in self.extras:
+            item = self._task_list_item_re.sub(self._task_list_item_sub, item)
+
+        return "<li>%s</li>\n" % item
+
+    def _process_list_items(self, list_str):
+        # Process the contents of a single ordered or unordered list,
+        # splitting it into individual list items.
+
+        # The $g_list_level global keeps track of when we're inside a list.
+        # Each time we enter a list, we increment it; when we leave a list,
+        # we decrement. If it's zero, we're not in a list anymore.
+        #
+        # We do this because when we're not inside a list, we want to treat
+        # something like this:
+        #
+        #       I recommend upgrading to version
+        #       8. Oops, now this line is treated
+        #       as a sub-list.
+        #
+        # As a single paragraph, despite the fact that the second line starts
+        # with a digit-period-space sequence.
+        #
+        # Whereas when we're inside a list (or sub-list), that line will be
+        # treated as the start of a sub-list. What a kludge, huh? This is
+        # an aspect of Markdown's syntax that's hard to parse perfectly
+        # without resorting to mind-reading. Perhaps the solution is to
+        # change the syntax rules such that sub-lists must start with a
+        # starting cardinal number; e.g. "1." or "a.".
+        self.list_level += 1
+        self._last_li_endswith_two_eols = False
+        list_str = list_str.rstrip('\n') + '\n'
+        list_str = self._list_item_re.sub(self._list_item_sub, list_str)
+        self.list_level -= 1
+        return list_str
+
+    def _get_pygments_lexer(self, lexer_name):
+        try:
+            from pygments import lexers, util
+        except ImportError:
+            return None
+        try:
+            return lexers.get_lexer_by_name(lexer_name)
+        except util.ClassNotFound:
+            return None
+
+    def _color_with_pygments(self, codeblock, lexer, **formatter_opts):
+        import pygments
+        import pygments.formatters
+
+        class HtmlCodeFormatter(pygments.formatters.HtmlFormatter):
+            def _wrap_code(self, inner):
+                """A function for use in a Pygments Formatter which
+                wraps in <code> tags.
+                """
+                yield 0, "<code>"
+                for tup in inner:
+                    yield tup
+                yield 0, "</code>"
+
+            def _add_newline(self, inner):
+                # Add newlines around the inner contents so that _strict_tag_block_re matches the outer div.
+                yield 0, "\n"
+                yield from inner
+                yield 0, "\n"
+
+            def wrap(self, source, outfile=None):
+                """Return the source with a code, pre, and div."""
+                if outfile is None:
+                    # pygments >= 2.12
+                    return self._add_newline(self._wrap_pre(self._wrap_code(source)))
+                else:
+                    # pygments < 2.12
+                    return self._wrap_div(self._add_newline(self._wrap_pre(self._wrap_code(source))))
+
+        formatter_opts.setdefault("cssclass", "codehilite")
+        formatter = HtmlCodeFormatter(**formatter_opts)
+        return pygments.highlight(codeblock, lexer, formatter)
+
+    def _code_block_sub(self, match):
+        codeblock = match.group(1)
+        codeblock = self._outdent(codeblock)
+        codeblock = self._detab(codeblock)
+        codeblock = codeblock.lstrip('\n')  # trim leading newlines
+        codeblock = codeblock.rstrip()      # trim trailing whitespace
+
+        pre_class_str = self._html_class_str_from_tag("pre")
+        code_class_str = self._html_class_str_from_tag("code")
+
+        codeblock = self._encode_code(codeblock)
+
+        return "\n<pre%s><code%s>%s\n</code></pre>\n" % (
+            pre_class_str, code_class_str, codeblock)
+
+    def _html_class_str_from_tag(self, tag):
+        """Get the appropriate ' class="..."' string (note the leading
+        space), if any, for the given tag.
+        """
+        if "html-classes" not in self.extras:
+            return ""
+        try:
+            html_classes_from_tag = self.extras["html-classes"]
+        except TypeError:
+            return ""
+        else:
+            if isinstance(html_classes_from_tag, dict):
+                if tag in html_classes_from_tag:
+                    return ' class="%s"' % html_classes_from_tag[tag]
+        return ""
+
+    @mark_stage(Stage.CODE_BLOCKS)
+    def _do_code_blocks(self, text):
+        """Process Markdown `<pre><code>` blocks."""
+        code_block_re = re.compile(r'''
+            (?:\n\n|\A\n?)
+            (               # $1 = the code block -- one or more lines, starting with a space/tab
+              (?:
+                (?:[ ]{%d} | \t)  # Lines must start with a tab or a tab-width of spaces
+                .*\n+
+              )+
+            )
+            ((?=^[ ]{0,%d}\S)|\Z)   # Lookahead for non-space at line-start, or end of doc
+            # Lookahead to make sure this block isn't already in a code block.
+            # Needed when syntax highlighting is being used.
+            (?!([^<]|<(/?)span)*\</code\>)
+            ''' % (self.tab_width, self.tab_width),
+            re.M | re.X)
+        return code_block_re.sub(self._code_block_sub, text)
+
+    # Rules for a code span:
+    # - backslash escapes are not interpreted in a code span
+    # - to include one or or a run of more backticks the delimiters must
+    #   be a longer run of backticks
+    # - cannot start or end a code span with a backtick; pad with a
+    #   space and that space will be removed in the emitted HTML
+    # See `test/tm-cases/escapes.text` for a number of edge-case
+    # examples.
+    _code_span_re = re.compile(r'''
+            (?<!\\)
+            (`+)        # \1 = Opening run of `
+            (?!`)       # See Note A test/tm-cases/escapes.text
+            (.+?)       # \2 = The code block
+            (?<!`)
+            \1          # Matching closer
+            (?!`)
+        ''', re.X | re.S)
+
+    def _code_span_sub(self, match):
+        c = match.group(2).strip(" \t")
+        c = self._encode_code(c)
+        return "<code%s>%s</code>" % (self._html_class_str_from_tag("code"), c)
+
+    @mark_stage(Stage.CODE_SPANS)
+    def _do_code_spans(self, text):
+        #   *   Backtick quotes are used for <code></code> spans.
+        #
+        #   *   You can use multiple backticks as the delimiters if you want to
+        #       include literal backticks in the code span. So, this input:
+        #
+        #         Just type ``foo `bar` baz`` at the prompt.
+        #
+        #       Will translate to:
+        #
+        #         <p>Just type <code>foo `bar` baz</code> at the prompt.</p>
+        #
+        #       There's no arbitrary limit to the number of backticks you
+        #       can use as delimters. If you need three consecutive backticks
+        #       in your code, use four for delimiters, etc.
+        #
+        #   *   You can use spaces to get literal backticks at the edges:
+        #
+        #         ... type `` `bar` `` ...
+        #
+        #       Turns to:
+        #
+        #         ... type <code>`bar`</code> ...
+        return self._code_span_re.sub(self._code_span_sub, text)
+
+    def _encode_code(self, text):
+        """Encode/escape certain characters inside Markdown code runs.
+        The point is that in code, these characters are literals,
+        and lose their special Markdown meanings.
+        """
+        replacements = [
+            # Encode all ampersands; HTML entities are not
+            # entities within a Markdown code span.
+            ('&', '&amp;'),
+            # Do the angle bracket song and dance:
+            ('<', '&lt;'),
+            ('>', '&gt;'),
+        ]
+        for before, after in replacements:
+            text = text.replace(before, after)
+        hashed = _hash_text(text)
+        self._code_table[text] = hashed
+        return hashed
+
+    _strong_re = re.compile(r"(\*\*|__)(?=\S)(.+?[*_]?)(?<=\S)\1", re.S)
+    _em_re = re.compile(r"(\*|_)(?=\S)(.*?\S)\1", re.S)
+
+    @mark_stage(Stage.ITALIC_AND_BOLD)
+    def _do_italics_and_bold(self, text):
+        # <strong> must go first:
+        text = self._strong_re.sub(r"<strong>\2</strong>", text)
+        text = self._em_re.sub(r"<em>\2</em>", text)
+        return text
+
+    _block_quote_base = r'''
+        (                           # Wrap whole match in \1
+          (
+            ^[ \t]*>%s[ \t]?        # '>' at the start of a line
+              .+\n                  # rest of the first line
+            (.+\n)*                 # subsequent consecutive lines
+          )+
+        )
+    '''
+    _block_quote_re = re.compile(_block_quote_base % '', re.M | re.X)
+    _block_quote_re_spoiler = re.compile(_block_quote_base % '[ \t]*?!?', re.M | re.X)
+    _bq_one_level_re = re.compile('^[ \t]*>[ \t]?', re.M)
+    _bq_one_level_re_spoiler = re.compile('^[ \t]*>[ \t]*?![ \t]?', re.M)
+    _bq_all_lines_spoilers = re.compile(r'\A(?:^[ \t]*>[ \t]*?!.*[\n\r]*)+\Z', re.M)
+    _html_pre_block_re = re.compile(r'(\s*<pre>.+?</pre>)', re.S)
+    def _dedent_two_spaces_sub(self, match):
+        return re.sub(r'(?m)^  ', '', match.group(1))
+
+    def _block_quote_sub(self, match):
+        bq = match.group(1)
+        is_spoiler = 'spoiler' in self.extras and self._bq_all_lines_spoilers.match(bq)
+        # trim one level of quoting
+        if is_spoiler:
+            bq = self._bq_one_level_re_spoiler.sub('', bq)
+        else:
+            bq = self._bq_one_level_re.sub('', bq)
+        # trim whitespace-only lines
+        bq = self._ws_only_line_re.sub('', bq)
+        bq = self._run_block_gamut(bq)          # recurse
+
+        bq = re.sub('(?m)^', '  ', bq)
+        # These leading spaces screw with <pre> content, so we need to fix that:
+        bq = self._html_pre_block_re.sub(self._dedent_two_spaces_sub, bq)
+
+        if is_spoiler:
+            return '<blockquote class="spoiler">\n%s\n</blockquote>\n\n' % bq
+        else:
+            return '<blockquote>\n%s\n</blockquote>\n\n' % bq
+
+    @mark_stage(Stage.BLOCK_QUOTES)
+    def _do_block_quotes(self, text):
+        if '>' not in text:
+            return text
+        if 'spoiler' in self.extras:
+            return self._block_quote_re_spoiler.sub(self._block_quote_sub, text)
+        else:
+            return self._block_quote_re.sub(self._block_quote_sub, text)
+
+    @mark_stage(Stage.PARAGRAPHS)
+    def _form_paragraphs(self, text):
+        # Strip leading and trailing lines:
+        text = text.strip('\n')
+
+        # Wrap <p> tags.
+        grafs = []
+        for i, graf in enumerate(re.split(r"\n{2,}", text)):
+            if graf in self.html_blocks:
+                # Unhashify HTML blocks
+                grafs.append(self.html_blocks[graf])
+            else:
+                cuddled_list = None
+                if "cuddled-lists" in self.extras:
+                    # Need to put back trailing '\n' for `_list_item_re`
+                    # match at the end of the paragraph.
+                    li = self._list_item_re.search(graf + '\n')
+                    # Two of the same list marker in this paragraph: a likely
+                    # candidate for a list cuddled to preceding paragraph
+                    # text (issue 33). Note the `[-1]` is a quick way to
+                    # consider numeric bullets (e.g. "1." and "2.") to be
+                    # equal.
+                    if (li and len(li.group(2)) <= 3
+                            and (
+                                    (li.group("next_marker") and li.group("marker")[-1] == li.group("next_marker")[-1])
+                                    or
+                                    li.group("next_marker") is None
+                            )
+                    ):
+                        start = li.start()
+                        cuddled_list = self._do_lists(graf[start:]).rstrip("\n")
+                        assert re.match(r'^<(?:ul|ol).*?>', cuddled_list)
+                        graf = graf[:start]
+
+                # Wrap <p> tags.
+                graf = self._run_span_gamut(graf)
+                grafs.append("<p%s>" % self._html_class_str_from_tag('p') + graf.lstrip(" \t") + "</p>")
+
+                if cuddled_list:
+                    grafs.append(cuddled_list)
+
+        return "\n\n".join(grafs)
+
+    def _add_footnotes(self, text):
+        if self.footnotes:
+            footer = [
+                '<div class="footnotes">',
+                '<hr' + self.empty_element_suffix,
+                '<ol>',
+            ]
+
+            if not self.footnote_title:
+                self.footnote_title = "Jump back to footnote %d in the text."
+            if not self.footnote_return_symbol:
+                self.footnote_return_symbol = "&#8617;"
+
+            # self.footnotes is generated in _strip_footnote_definitions, which runs re.sub on the whole
+            # text. This means that the dict keys are inserted in order of appearance. Use the dict to
+            # sort footnote ids by that same order
+            self.footnote_ids.sort(key=lambda a: list(self.footnotes.keys()).index(a))
+            for i, id in enumerate(self.footnote_ids):
+                if i != 0:
+                    footer.append('')
+                footer.append('<li id="fn-%s">' % id)
+                footer.append(self._run_block_gamut(self.footnotes[id]))
+                try:
+                    backlink = ('<a href="#fnref-%s" ' +
+                            'class="footnoteBackLink" ' +
+                            'title="' + self.footnote_title + '">' +
+                            self.footnote_return_symbol +
+                            '</a>') % (id, i+1)
+                except TypeError:
+                    log.debug("Footnote error. `footnote_title` "
+                              "must include parameter. Using defaults.")
+                    backlink = ('<a href="#fnref-%s" '
+                        'class="footnoteBackLink" '
+                        'title="Jump back to footnote %d in the text.">'
+                        '&#8617;</a>' % (id, i+1))
+
+                if footer[-1].endswith("</p>"):
+                    footer[-1] = footer[-1][:-len("</p>")] \
+                        + '&#160;' + backlink + "</p>"
+                else:
+                    footer.append("\n<p>%s</p>" % backlink)
+                footer.append('</li>')
+            footer.append('</ol>')
+            footer.append('</div>')
+            return text + '\n\n' + '\n'.join(footer)
+        else:
+            return text
+
+    _naked_lt_re = re.compile(r'<(?![a-z/?\$!])', re.I)
+    _naked_gt_re = re.compile(r'''(?<![a-z0-9?!/'"-])>''', re.I)
+
+    def _encode_amps_and_angles(self, text):
+        # Smart processing for ampersands and angle brackets that need
+        # to be encoded.
+        text = _AMPERSAND_RE.sub('&amp;', text)
+
+        # Encode naked <'s
+        text = self._naked_lt_re.sub('&lt;', text)
+
+        # Encode naked >'s
+        # Note: Other markdown implementations (e.g. Markdown.pl, PHP
+        # Markdown) don't do this.
+        text = self._naked_gt_re.sub('&gt;', text)
+        return text
+
+    _incomplete_tags_re = re.compile(r"<(!--|/?\w+?(?!\w)\s*?.+?[\s/]+?)")
+
+    def _encode_incomplete_tags(self, text):
+        if self.safe_mode not in ("replace", "escape"):
+            return text
+
+        if text.endswith(">"):
+            return text  # this is not an incomplete tag, this is a link in the form <http://x.y.z>
+
+        def incomplete_tags_sub(match):
+            return match.group().replace('<', '&lt;')
+
+        return self._incomplete_tags_re.sub(incomplete_tags_sub, text)
+
+    def _encode_backslash_escapes(self, text):
+        for ch, escape in list(self._escape_table.items()):
+            text = text.replace("\\"+ch, escape)
+        return text
+
+    _auto_link_re = re.compile(r'<((https?|ftp):[^\'">\s]+)>', re.I)
+    def _auto_link_sub(self, match):
+        g1 = match.group(1)
+        return '<a href="%s">%s</a>' % (self._protect_url(g1), g1)
+
+    _auto_email_link_re = re.compile(r"""
+          <
+           (?:mailto:)?
+          (
+              [-.\w]+
+              \@
+              [-\w]+(\.[-\w]+)*\.[a-z]+
+          )
+          >
+        """, re.I | re.X | re.U)
+    def _auto_email_link_sub(self, match):
+        return self._encode_email_address(
+            self._unescape_special_chars(match.group(1)))
+
+    def _do_auto_links(self, text):
+        text = self._auto_link_re.sub(self._auto_link_sub, text)
+        text = self._auto_email_link_re.sub(self._auto_email_link_sub, text)
+        return text
+
+    def _encode_email_address(self, addr):
+        #  Input: an email address, e.g. "foo@example.com"
+        #
+        #  Output: the email address as a mailto link, with each character
+        #      of the address encoded as either a decimal or hex entity, in
+        #      the hopes of foiling most address harvesting spam bots. E.g.:
+        #
+        #    <a href="&#x6D;&#97;&#105;&#108;&#x74;&#111;:&#102;&#111;&#111;&#64;&#101;
+        #       x&#x61;&#109;&#x70;&#108;&#x65;&#x2E;&#99;&#111;&#109;">&#102;&#111;&#111;
+        #       &#64;&#101;x&#x61;&#109;&#x70;&#108;&#x65;&#x2E;&#99;&#111;&#109;</a>
+        #
+        #  Based on a filter by Matthew Wickline, posted to the BBEdit-Talk
+        #  mailing list: <http://tinyurl.com/yu7ue>
+        chars = [_xml_encode_email_char_at_random(ch)
+                 for ch in "mailto:" + addr]
+        # Strip the mailto: from the visible part.
+        addr = '<a href="%s">%s</a>' \
+               % (''.join(chars), ''.join(chars[7:]))
+        return addr
+
+    def _unescape_special_chars(self, text):
+        # Swap back in all the special characters we've hidden.
+        hashmap = tuple(self._escape_table.items()) + tuple(self._code_table.items())
+        # html_blocks table is in format {hash: item} compared to usual {item: hash}
+        hashmap += tuple(tuple(reversed(i)) for i in self.html_blocks.items())
+        while True:
+            orig_text = text
+            for ch, hash in hashmap:
+                text = text.replace(hash, ch)
+            if text == orig_text:
+                break
+        return text
+
+    def _outdent(self, text):
+        # Remove one level of line-leading tabs or spaces
+        return self._outdent_re.sub('', text)
+
+    @staticmethod
+    def _uniform_outdent(text, min_outdent=None, max_outdent=None):
+        '''
+        Removes the smallest common leading indentation from each (non empty)
+        line of `text` and returns said indent along with the outdented text.
+
+        Args:
+            min_outdent: make sure the smallest common whitespace is at least this size
+            max_outdent: the maximum amount a line can be outdented by
+        '''
+
+        # find the leading whitespace for every line
+        whitespace = [
+            re.findall(r'^[ \t]*', line)[0] if line else None
+            for line in text.splitlines()
+        ]
+        whitespace_not_empty = [i for i in whitespace if i is not None]
+
+        # if no whitespace detected (ie: no lines in code block, issue #505)
+        if not whitespace_not_empty:
+            return '', text
+
+        # get minimum common whitespace
+        outdent = min(whitespace_not_empty)
+        # adjust min common ws to be within bounds
+        if min_outdent is not None:
+            outdent = min([i for i in whitespace_not_empty if i >= min_outdent] or [min_outdent])
+        if max_outdent is not None:
+            outdent = min(outdent, max_outdent)
+
+        outdented = []
+        for line_ws, line in zip(whitespace, text.splitlines(True)):
+            if line.startswith(outdent):
+                # if line starts with smallest common ws, dedent it
+                outdented.append(line.replace(outdent, '', 1))
+            elif line_ws is not None and line_ws < outdent:
+                # if less indented than min common whitespace then outdent as much as possible
+                outdented.append(line.replace(line_ws, '', 1))
+            else:
+                outdented.append(line)
+
+        return outdent, ''.join(outdented)
+
+    @staticmethod
+    def _uniform_indent(text, indent, include_empty_lines=False, indent_empty_lines=False):
+        '''
+        Uniformly indent a block of text by a fixed amount
+
+        Args:
+            text: the text to indent
+            indent: a string containing the indent to apply
+            include_empty_lines: don't remove whitespace only lines
+            indent_empty_lines: indent whitespace only lines with the rest of the text
+        '''
+        blocks = []
+        for line in text.splitlines(True):
+            if line.strip() or indent_empty_lines:
+                blocks.append(indent + line)
+            elif include_empty_lines:
+                blocks.append(line)
+            else:
+                blocks.append('')
+        return ''.join(blocks)
+
+    @staticmethod
+    def _match_overlaps_substr(text, match, substr):
+        '''
+        Checks if a regex match overlaps with a substring in the given text.
+        '''
+        for instance in re.finditer(re.escape(substr), text):
+            start, end = instance.span()
+            if start <= match.start() <= end:
+                return True
+            if start <= match.end() <= end:
+                return True
+        return False
+
+
+class MarkdownWithExtras(Markdown):
+    """A markdowner class that enables most extras:
+
+    - footnotes
+    - fenced-code-blocks (only highlights code if 'pygments' Python module on path)
+
+    These are not included:
+    - pyshell (specific to Python-related documenting)
+    - code-friendly (because it *disables* part of the syntax)
+    - link-patterns (because you need to specify some actual
+      link-patterns anyway)
+    """
+    extras = ["footnotes", "fenced-code-blocks"]
+
+
+# ----------------------------------------------------------
+# Extras
+# ----------------------------------------------------------
+
+# Base classes
+# ----------------------------------------------------------
+
+class Extra(ABC):
+    _registry = {}
+    _exec_order: Dict[Stage, Tuple[List['Extra'], List['Extra']]] = {}
+
+    name: str
+    '''
+    An identifiable name that users can use to invoke the extra
+    in the Markdown class
+    '''
+    order: Tuple[Iterable[Union[Stage, 'Extra']], Iterable[Union[Stage, 'Extra']]]
+    '''
+    Tuple of two iterables containing the stages/extras this extra will run before and
+    after, respectively
+    '''
+
+    def __init__(self, md: Markdown, options: Optional[dict]):
+        '''
+        Args:
+            md: An instance of `Markdown`
+            options: a dict of settings to alter the extra's behaviour
+        '''
+        self.md = md
+        self.options = options if options is not None else {}
+
+    @classmethod
+    def deregister(cls):
+        '''
+        Removes the class from the extras registry and unsets its execution order.
+        '''
+        if cls.name in cls._registry:
+            del cls._registry[cls.name]
+
+        for exec_order in Extra._exec_order.values():
+            # find everywhere this extra is mentioned and remove it
+            for section in exec_order:
+                while cls in section:
+                    section.remove(cls)
+
+    @classmethod
+    def register(cls):
+        '''
+        Registers the class for use with `Markdown` and calculates its execution order based on
+        the `order` class attribute.
+        '''
+        cls._registry[cls.name] = cls
+
+        for index, item in enumerate((*cls.order[0], *cls.order[1])):
+            before = index < len(cls.order[0])
+            if not isinstance(item, Stage) and issubclass(item, Extra):
+                # eg: FencedCodeBlocks
+                for exec_orders in Extra._exec_order.values():
+                    # insert this extra everywhere the other one is mentioned
+                    for section in exec_orders:
+                        if item in section:
+                            to_index = section.index(item)
+                            if not before:
+                                to_index += 1
+                            section.insert(to_index, cls)
+            else:
+                # eg: Stage.PREPROCESS
+                Extra._exec_order.setdefault(item, ([], []))
+                if cls in Extra._exec_order[item][0 if before else 1]:
+                    # extra is already runnig after this stage. Don't duplicate that effort
+                    continue
+                if before:
+                    Extra._exec_order[item][0].insert(0, cls)
+                else:
+                    Extra._exec_order[item][1].append(cls)
+
+    @abstractmethod
+    def run(self, text: str) -> str:
+        '''
+        Run the extra against the given text.
+
+        Returns:
+            The new text after being modified by the extra
+        '''
+        ...
+
+    def test(self, text: str) -> bool:
+        '''
+        Check a section of markdown to see if this extra should be run upon it.
+        The default implementation will always return True but it's recommended to override
+        this behaviour to improve performance.
+        '''
+        return True
+
+
+class ItalicAndBoldProcessor(Extra):
+    '''
+    An ABC that provides hooks for dealing with italics and bold syntax.
+    This class is set to trigger both before AND after the italics and bold stage.
+    This allows any child classes to intercept instances of bold or italic syntax and
+    change the output or hash it to prevent it from being processed.
+
+    After the I&B stage any hashes in the `hash_tables` instance variable are replaced.
+    '''
+    name = 'italic-and-bold-processor'
+    order = (Stage.ITALIC_AND_BOLD,), (Stage.ITALIC_AND_BOLD,)
+
+    strong_re = Markdown._strong_re
+    em_re = Markdown._em_re
+
+    def __init__(self, md: Markdown, options: dict):
+        super().__init__(md, options)
+        self.hash_table = {}
+
+    def run(self, text):
+        if self.md.order < Stage.ITALIC_AND_BOLD:
+            text = self.strong_re.sub(self.sub, text)
+            text = self.em_re.sub(self.sub, text)
+        else:
+            # put any hashed values back
+            for key, substr in self.hash_table.items():
+                text = text.replace(key, substr)
+        return text
+
+    @abstractmethod
+    def sub(self, match):
+        # do nothing. Let `Markdown._do_italics_and_bold` do its thing later
+        return match.string[match.start(): match.end()]
+
+    def sub_hash(self, match):
+        substr = match.string[match.start(): match.end()]
+        key = _hash_text(substr)
+        self.hash_table[key] = substr
+        return key
+
+    def test(self, text):
+        if self.md.order < Stage.ITALIC_AND_BOLD:
+            return '*' in text or '_' in text
+        return self.hash_table and re.search(r'md5-[0-9a-z]{32}', text)
+
+# User facing extras
+# ----------------------------------------------------------
+
+
+class Admonitions(Extra):
+    '''
+    Enable parsing of RST admonitions
+    '''
+
+    name = 'admonitions'
+    order = (Stage.BLOCK_GAMUT, Stage.LINK_DEFS), ()
+
+    admonitions = r'admonition|attention|caution|danger|error|hint|important|note|tip|warning'
+
+    admonitions_re = re.compile(r'''
+        ^(\ *)\.\.\ (%s)::\ *                # $1 leading indent, $2 the admonition
+        (.*)?                                # $3 admonition title
+        ((?:\s*\n\1\ {3,}.*)+?)              # $4 admonition body (required)
+        (?=\s*(?:\Z|\n{4,}|\n\1?\ {0,2}\S))  # until EOF, 3 blank lines or something less indented
+        ''' % admonitions,
+        re.IGNORECASE | re.MULTILINE | re.VERBOSE
+    )
+
+    def test(self, text):
+        return self.admonitions_re.search(text) is not None
+
+    def sub(self, match):
+        lead_indent, admonition_name, title, body = match.groups()
+
+        admonition_type = '<strong>%s</strong>' % admonition_name
+
+        # figure out the class names to assign the block
+        if admonition_name.lower() == 'admonition':
+            admonition_class = 'admonition'
+        else:
+            admonition_class = 'admonition %s' % admonition_name.lower()
+
+        # titles are generally optional
+        if title:
+            title = '<em>%s</em>' % title
+
+        # process the admonition body like regular markdown
+        body = self.md._run_block_gamut("\n%s\n" % self.md._uniform_outdent(body)[1])
+
+        # indent the body before placing inside the aside block
+        admonition = self.md._uniform_indent(
+            '%s\n%s\n\n%s\n' % (admonition_type, title, body),
+            self.md.tab, False
+        )
+        # wrap it in an aside
+        admonition = '<aside class="%s">\n%s</aside>' % (admonition_class, admonition)
+        # now indent the whole admonition back to where it started
+        return self.md._uniform_indent(admonition, lead_indent, False)
+
+    def run(self, text):
+        return self.admonitions_re.sub(self.sub, text)
+
+
+class Breaks(Extra):
+    name = 'breaks'
+    order = (), (Stage.ITALIC_AND_BOLD,)
+
+    def run(self, text):
+        on_backslash = self.options.get('on_backslash', False)
+        on_newline = self.options.get('on_newline', False)
+
+        if on_backslash and on_newline:
+            pattern = r' *\\?'
+        elif on_backslash:
+            pattern = r'(?: *\\| {2,})'
+        elif on_newline:
+            pattern = r' *'
+        else:
+            pattern = r' {2,}'
+
+        break_tag = "<br%s\n" % self.md.empty_element_suffix
+        text = re.sub(pattern + r"\n(?!\<(?:\/?(ul|ol|li))\>)", break_tag, text)
+
+        return text
+
+
+class CodeFriendly(ItalicAndBoldProcessor):
+    '''
+    Disable _ and __ for em and strong.
+    '''
+    name = 'code-friendly'
+
+    def sub(self, match):
+        syntax = match.group(1)
+        if '_' not in syntax:
+            return super().sub(match)
+        text = match.string[match.start(): match.end()]
+        key = _hash_text(text)
+        self.hash_table[key] = text
+        return key
+
+
+class FencedCodeBlocks(Extra):
+    '''
+    Allows a code block to not have to be indented
+    by fencing it with '```' on a line before and after. Based on
+    <http://github.github.com/github-flavored-markdown/> with support for
+    syntax highlighting.
+    '''
+
+    name = 'fenced-code-blocks'
+    order = (Stage.LINK_DEFS, Stage.BLOCK_GAMUT), (Stage.PREPROCESS,)
+
+    fenced_code_block_re = re.compile(r'''
+        (?:\n+|\A\n?|(?<=\n))
+        (^[ \t]*`{3,})\s{0,99}?([\w+-]+)?\s{0,99}?\n  # $1 = opening fence (captured for back-referencing), $2 = optional lang
+        (.*?)                             # $3 = code block content
+        \1[ \t]*\n                      # closing fence
+        ''', re.M | re.X | re.S)
+
+    def test(self, text):
+        if '```' not in text:
+            return False
+        if self.md.stage == Stage.PREPROCESS and not self.md.safe_mode:
+            return True
+        if self.md.stage == Stage.LINK_DEFS and self.md.safe_mode:
+            return True
+        return self.md.stage == Stage.BLOCK_GAMUT
+
+    def _code_block_with_lexer_sub(self, codeblock, leading_indent, lexer):
+        formatter_opts = self.md.extras['fenced-code-blocks'] or {}
+
+        def unhash_code(codeblock):
+            for key, sanitized in list(self.md.html_spans.items()):
+                codeblock = codeblock.replace(key, sanitized)
+            replacements = [
+                ("&amp;", "&"),
+                ("&lt;", "<"),
+                ("&gt;", ">")
+            ]
+            for old, new in replacements:
+                codeblock = codeblock.replace(old, new)
+            return codeblock
+        # remove leading indent from code block
+        _, codeblock = self.md._uniform_outdent(codeblock, max_outdent=leading_indent)
+
+        codeblock = unhash_code(codeblock)
+        colored = self.md._color_with_pygments(codeblock, lexer,
+                                               **formatter_opts)
+
+        # add back the indent to all lines
+        return "\n%s\n" % self.md._uniform_indent(colored, leading_indent, True)
+
+    def tags(self, lexer_name) -> tuple:
+        '''
+        Returns the tags that the encoded code block will be wrapped in, based
+        upon the lexer name.
+
+        This function can be overridden by subclasses to piggy-back off of the
+        fenced code blocks syntax (see `Mermaid` extra).
+
+        Returns:
+            The opening and closing tags, as strings within a tuple
+        '''
+        pre_class = self.md._html_class_str_from_tag('pre')
+        if "highlightjs-lang" in self.md.extras and lexer_name:
+            code_class = ' class="%s language-%s"' % (lexer_name, lexer_name)
+        else:
+            code_class = self.md._html_class_str_from_tag('code')
+        return ('<pre%s><code%s>' % (pre_class, code_class), '</code></pre>')
+
+    def sub(self, match):
+        lexer_name = match.group(2)
+        codeblock = match.group(3)
+        codeblock = codeblock[:-1]  # drop one trailing newline
+
+        # Use pygments only if not using the highlightjs-lang extra
+        if lexer_name and "highlightjs-lang" not in self.md.extras:
+            lexer = self.md._get_pygments_lexer(lexer_name)
+            if lexer:
+                leading_indent = ' '*(len(match.group(1)) - len(match.group(1).lstrip()))
+                return self._code_block_with_lexer_sub(codeblock, leading_indent, lexer)
+
+        # Fenced code blocks need to be outdented before encoding, and then reapplied
+        leading_indent = ' ' * (len(match.group(1)) - len(match.group(1).lstrip()))
+        if codeblock:
+            # only run the codeblock through the outdenter if not empty
+            leading_indent, codeblock = self.md._uniform_outdent(codeblock, max_outdent=leading_indent)
+
+        codeblock = self.md._encode_code(codeblock)
+
+        tags = self.tags(lexer_name)
+
+        return "\n%s%s%s\n%s\n" % (leading_indent, tags[0], codeblock, tags[1])
+
+    def run(self, text):
+        return self.fenced_code_block_re.sub(self.sub, text)
+
+class Latex(Extra):
+    '''
+    Convert $ and $$ to <math> and </math> tags for inline and block math.
+    '''
+    name = 'latex'
+    order = (Stage.HASH_HTML,), ()
+
+    _single_dollar_re = re.compile(r'(?<!\$)\$(?!\$)(.*?)\$')
+    _double_dollar_re = re.compile(r'\$\$(.*?)\$\$', re.DOTALL)
+
+    _pre_code_block_re = re.compile(r"<pre>(.*?)</pre>", re.DOTALL)
+
+    converter = None
+    code_blocks = {}
+
+    def _convert_single_match(self, match):
+        return self.converter.convert(match.group(1))
+
+    def _convert_double_match(self, match):
+        return self.converter.convert(match.group(1).replace(r"\n", ''), display="block")
+
+    def code_placeholder(self, match):
+        #print("found match:", match, match.group(0), match.group(1))
+        placeholder = f"<!--CODE_BLOCK_{len(self.code_blocks)}-->"
+        self.code_blocks[placeholder] = match.group(0)
+        return placeholder
+
+    def run(self, text):
+        try:
+            import latex2mathml.converter
+            self.converter = latex2mathml.converter
+        except ImportError:
+            raise ImportError('The "latex" extra requires the "latex2mathml" package to be installed.')
+
+        text = self._pre_code_block_re.sub(self.code_placeholder, text)
+
+        #print("Temp Text", text)
+
+        text = self._single_dollar_re.sub(self._convert_single_match, text)
+        text = self._double_dollar_re.sub(self._convert_double_match, text)
+
+        for placeholder, code_block in self.code_blocks.items():
+            text = text.replace(placeholder, code_block)
+
+        return text
+
+
+
+
+
+class LinkPatterns(Extra):
+    '''
+    Auto-link given regex patterns in text (e.g. bug number
+    references, revision number references).
+    '''
+    name = 'link-patterns'
+    order = (Stage.LINKS,), ()
+
+    _basic_link_re = re.compile(r'!?\[.*?\]\(.*?\)')
+
+    def run(self, text):
+        link_from_hash = {}
+        for regex, repl in self.options:
+            replacements = []
+            for match in regex.finditer(text):
+                if any(self.md._match_overlaps_substr(text, match, h) for h in link_from_hash):
+                    continue
+
+                if hasattr(repl, "__call__"):
+                    href = repl(match)
+                else:
+                    href = match.expand(repl)
+                replacements.append((match.span(), href))
+            for (start, end), href in reversed(replacements):
+
+                # Do not match against links inside brackets.
+                if text[start - 1:start] == '[' and text[end:end + 1] == ']':
+                    continue
+
+                # Do not match against links in the standard markdown syntax.
+                if text[start - 2:start] == '](' or text[end:end + 2] == '")':
+                    continue
+
+                # Do not match against links which are escaped.
+                if text[start - 3:start] == '"""' and text[end:end + 3] == '"""':
+                    text = text[:start - 3] + text[start:end] + text[end + 3:]
+                    continue
+
+                # search the text for anything that looks like a link
+                is_inside_link = False
+                for link_re in (self.md._auto_link_re, self._basic_link_re):
+                    for match in link_re.finditer(text):
+                        if any((r[0] <= start and end <= r[1]) for r in match.regs):
+                            # if the link pattern start and end pos is within the bounds of
+                            # something that looks like a link, then don't process it
+                            is_inside_link = True
+                            break
+                    else:
+                        continue
+                    break
+
+                if is_inside_link:
+                    continue
+
+                escaped_href = (
+                    href.replace('"', '&quot;')  # b/c of attr quote
+                        # To avoid markdown <em> and <strong>:
+                        .replace('*', self.md._escape_table['*'])
+                        .replace('_', self.md._escape_table['_']))
+                link = '<a href="%s">%s</a>' % (escaped_href, text[start:end])
+                hash = _hash_text(link)
+                link_from_hash[hash] = link
+                text = text[:start] + hash + text[end:]
+        for hash, link in list(link_from_hash.items()):
+            text = text.replace(hash, link)
+        return text
+
+    def test(self, text):
+        return True
+
+
+class MarkdownInHTML(Extra):
+    '''
+    Allow the use of `markdown="1"` in a block HTML tag to
+    have markdown processing be done on its contents. Similar to
+    <http://michelf.com/projects/php-markdown/extra/#markdown-attr> but with
+    some limitations.
+    '''
+    name = 'markdown-in-html'
+    order = (), (Stage.HASH_HTML,)
+
+    def run(self, text):
+        def callback(block):
+            indent, block = self.md._uniform_outdent(block)
+            block = self.md._hash_html_block_sub(block)
+            block = self.md._uniform_indent(block, indent, include_empty_lines=True, indent_empty_lines=False)
+            return block
+
+        return self.md._strict_tag_block_sub(text, self.md._block_tags_a, callback, True)
+
+    def test(self, text):
+        return True
+
+
+class Mermaid(FencedCodeBlocks):
+    name = 'mermaid'
+    order = (FencedCodeBlocks,), ()
+
+    def tags(self, lexer_name):
+        if lexer_name == 'mermaid':
+            return ('<pre class="mermaid-pre"><div class="mermaid">', '</div></pre>')
+        return super().tags(lexer_name)
+
+
+class MiddleWordEm(ItalicAndBoldProcessor):
+    '''
+    Allows or disallows emphasis syntax in the middle of words,
+    defaulting to allow. Disabling this means that `this_text_here` will not be
+    converted to `this<em>text</em>here`.
+    '''
+    name = 'middle-word-em'
+    order = (CodeFriendly,), (Stage.ITALIC_AND_BOLD,)
+
+    def __init__(self, md: Markdown, options: Union[dict, bool]):
+        '''
+        Args:
+            md: the markdown instance
+            options: can be bool for backwards compatibility but will be converted to a dict
+                in the constructor. All options are:
+                - allowed (bool): whether to allow emphasis in the middle of a word.
+                    If `options` is a bool it will be placed under this key.
+        '''
+        if isinstance(options, bool):
+            options = {'allowed': options}
+        options.setdefault('allowed', True)
+        super().__init__(md, options)
+
+        self.liberal_em_re = self.em_re
+        if not options['allowed']:
+            self.em_re = re.compile(r'(?<=\b)%s(?=\b)' % self.liberal_em_re.pattern, self.liberal_em_re.flags)
+
+    def run(self, text):
+        # run strong and whatnot first
+        # this also will process all strict ems
+        text = super().run(text)
+        if self.md.order < self.md.stage:
+            # hash all non-valid ems
+            text = self.liberal_em_re.sub(self.sub_hash, text)
+        return text
+
+    def sub(self, match):
+        syntax = match.group(1)
+        if len(syntax) != 1:
+            # strong syntax
+            return super().sub(match)
+        return '<em>%s</em>' % match.group(2)
+
+    def sub_hash(self, match):
+        text = match.string[match.start(): match.end()]
+        key = _hash_text(text)
+        self.hash_table[key] = text
+        return key
+
+
+class Numbering(Extra):
+    '''
+    Support of generic counters.  Non standard extension to
+    allow sequential numbering of figures, tables, equations, exhibits etc.
+    '''
+
+    name = 'numbering'
+    order = (Stage.LINK_DEFS,), ()
+
+    def test(self, text):
+        return True
+
+    def run(self, text):
+        # First pass to define all the references
+        regex_defns = re.compile(r'''
+            \[\#(\w+) # the counter.  Open square plus hash plus a word \1
+            ([^@]*)   # Some optional characters, that aren't an @. \2
+            @(\w+)       # the id.  Should this be normed? \3
+            ([^\]]*)\]   # The rest of the text up to the terminating ] \4
+            ''', re.VERBOSE)
+        regex_subs = re.compile(r"\[@(\w+)\s*\]")  # [@ref_id]
+        counters = {}
+        references = {}
+        replacements = []
+        definition_html = '<figcaption class="{}" id="counter-ref-{}">{}{}{}</figcaption>'
+        reference_html = '<a class="{}" href="#counter-ref-{}">{}</a>'
+        for match in regex_defns.finditer(text):
+            # We must have four match groups otherwise this isn't a numbering reference
+            if len(match.groups()) != 4:
+                continue
+            counter = match.group(1)
+            text_before = match.group(2).strip()
+            ref_id = match.group(3)
+            text_after = match.group(4)
+            number = counters.get(counter, 1)
+            references[ref_id] = (number, counter)
+            replacements.append((match.start(0),
+                                 definition_html.format(counter,
+                                                        ref_id,
+                                                        text_before,
+                                                        number,
+                                                        text_after),
+                                 match.end(0)))
+            counters[counter] = number + 1
+        for repl in reversed(replacements):
+            text = text[:repl[0]] + repl[1] + text[repl[2]:]
+
+        # Second pass to replace the references with the right
+        # value of the counter
+        # Fwiw, it's vaguely annoying to have to turn the iterator into
+        # a list and then reverse it but I can't think of a better thing to do.
+        for match in reversed(list(regex_subs.finditer(text))):
+            number, counter = references.get(match.group(1), (None, None))
+            if number is not None:
+                repl = reference_html.format(counter,
+                                             match.group(1),
+                                             number)
+            else:
+                repl = reference_html.format(match.group(1),
+                                             'countererror',
+                                             '?' + match.group(1) + '?')
+            if "smarty-pants" in self.md.extras:
+                repl = repl.replace('"', self.md._escape_table['"'])
+
+            text = text[:match.start()] + repl + text[match.end():]
+        return text
+
+
+class PyShell(Extra):
+    '''
+    Treats unindented Python interactive shell sessions as <code>
+    blocks.
+    '''
+
+    name = 'pyshell'
+    order = (), (Stage.LISTS,)
+
+    def test(self, text):
+        return ">>>" in text
+
+    def sub(self, match):
+        if "fenced-code-blocks" in self.md.extras:
+            dedented = _dedent(match.group(0))
+            return self.md.extra_classes['fenced-code-blocks'].run("```pycon\n" + dedented + "```\n")
+
+        lines = match.group(0).splitlines(0)
+        _dedentlines(lines)
+        indent = ' ' * self.md.tab_width
+        s = ('\n'  # separate from possible cuddled paragraph
+             + indent + ('\n'+indent).join(lines)
+             + '\n')
+        return s
+
+    def run(self, text):
+        less_than_tab = self.md.tab_width - 1
+        _pyshell_block_re = re.compile(r"""
+            ^([ ]{0,%d})>>>[ ].*\n  # first line
+            ^(\1[^\S\n]*\S.*\n)*    # any number of subsequent lines with at least one character
+            (?=^\1?\n|\Z)           # ends with a blank line or end of document
+            """ % less_than_tab, re.M | re.X)
+
+        return _pyshell_block_re.sub(self.sub, text)
+
+
+class SmartyPants(Extra):
+    '''
+    Replaces ' and " with curly quotation marks or curly
+    apostrophes.  Replaces --, ---, ..., and . . . with en dashes, em dashes,
+    and ellipses.
+    '''
+    name = 'smarty-pants'
+    order = (), (Stage.SPAN_GAMUT,)
+
+    _opening_single_quote_re = re.compile(r"(?<!\S)'(?=\S)")
+    _opening_double_quote_re = re.compile(r'(?<!\S)"(?=\S)')
+    _closing_single_quote_re = re.compile(r"(?<=\S)'")
+    _closing_double_quote_re = re.compile(r'(?<=\S)"(?=(\s|,|;|\.|\?|!|$))')
+    # "smarty-pants" extra: Very liberal in interpreting a single prime as an
+    # apostrophe; e.g. ignores the fact that "round", "bout", "twer", and
+    # "twixt" can be written without an initial apostrophe. This is fine because
+    # using scare quotes (single quotation marks) is rare.
+    _apostrophe_year_re = re.compile(r"'(\d\d)(?=(\s|,|;|\.|\?|!|$))")
+    _contractions = ["tis", "twas", "twer", "neath", "o", "n",
+        "round", "bout", "twixt", "nuff", "fraid", "sup"]
+
+
+    def contractions(self, text):
+        text = self._apostrophe_year_re.sub(r"&#8217;\1", text)
+        for c in self._contractions:
+            text = text.replace("'%s" % c, "&#8217;%s" % c)
+            text = text.replace("'%s" % c.capitalize(),
+                "&#8217;%s" % c.capitalize())
+        return text
+
+    def run(self, text):
+        """Fancifies 'single quotes', "double quotes", and apostrophes.
+        Converts --, ---, and ... into en dashes, em dashes, and ellipses.
+
+        Inspiration is: <http://daringfireball.net/projects/smartypants/>
+        See "test/tm-cases/smarty_pants.text" for a full discussion of the
+        support here and
+        <http://code.google.com/p/python-markdown2/issues/detail?id=42> for a
+        discussion of some diversion from the original SmartyPants.
+        """
+        if "'" in text:  # guard for perf
+            text = self.contractions(text)
+            text = self._opening_single_quote_re.sub("&#8216;", text)
+            text = self._closing_single_quote_re.sub("&#8217;", text)
+
+        if '"' in text:  # guard for perf
+            text = self._opening_double_quote_re.sub("&#8220;", text)
+            text = self._closing_double_quote_re.sub("&#8221;", text)
+
+        text = text.replace("---", "&#8212;")
+        text = text.replace("--", "&#8211;")
+        text = text.replace("...", "&#8230;")
+        text = text.replace(" . . . ", "&#8230;")
+        text = text.replace(". . .", "&#8230;")
+
+        # TODO: Temporary hack to fix https://github.com/trentm/python-markdown2/issues/150
+        if "footnotes" in self.md.extras and "footnote-ref" in text:
+            # Quotes in the footnote back ref get converted to "smart" quotes
+            # Change them back here to ensure they work.
+            text = text.replace('class="footnote-ref&#8221;', 'class="footnote-ref"')
+
+        return text
+
+    def test(self, text):
+        return "'" in text or '"' in text
+
+
+class Strike(Extra):
+    '''
+    Text inside of double tilde is ~~strikethrough~~
+    '''
+    name = 'strike'
+    order = (Stage.ITALIC_AND_BOLD,), ()
+
+    _strike_re = re.compile(r"~~(?=\S)(.+?)(?<=\S)~~", re.S)
+
+    def run(self, text):
+        return self._strike_re.sub(r"<s>\1</s>", text)
+
+    def test(self, text):
+        return '~~' in text
+
+
+class Tables(Extra):
+    '''
+    Tables using the same format as GFM
+    <https://help.github.com/articles/github-flavored-markdown#tables> and
+    PHP-Markdown Extra <https://michelf.ca/projects/php-markdown/extra/#table>.
+    '''
+    name = 'tables'
+    order = (), (Stage.LISTS,)
+
+    def run(self, text):
+        """Copying PHP-Markdown and GFM table syntax. Some regex borrowed from
+        https://github.com/michelf/php-markdown/blob/lib/Michelf/Markdown.php#L2538
+        """
+        less_than_tab = self.md.tab_width - 1
+        table_re = re.compile(r'''
+                (?:(?<=\n)|\A\n?)             # leading blank line
+
+                ^[ ]{0,%d}                      # allowed whitespace
+                (.*[|].*)[ ]*\n                   # $1: header row (at least one pipe)
+
+                ^[ ]{0,%d}                      # allowed whitespace
+                (                               # $2: underline row
+                    # underline row with leading bar
+                    (?:  \|\ *:?-+:?\ *  )+  \|? \s?[ ]*\n
+                    |
+                    # or, underline row without leading bar
+                    (?:  \ *:?-+:?\ *\|  )+  (?:  \ *:?-+:?\ *  )? \s?[ ]*\n
+                )
+
+                (                               # $3: data rows
+                    (?:
+                        ^[ ]{0,%d}(?!\ )         # ensure line begins with 0 to less_than_tab spaces
+                        .*\|.*[ ]*\n
+                    )+
+                )
+            ''' % (less_than_tab, less_than_tab, less_than_tab), re.M | re.X)
+        return table_re.sub(self.sub, text)
+
+    def sub(self, match):
+        trim_space_re = '^[ \t\n]+|[ \t\n]+$'
+        trim_bar_re = r'^\||\|$'
+        split_bar_re = r'^\||(?<![\`\\])\|'
+        escape_bar_re = r'\\\|'
+
+        head, underline, body = match.groups()
+
+        # Determine aligns for columns.
+        cols = [re.sub(escape_bar_re, '|', cell.strip()) for cell in re.split(split_bar_re, re.sub(trim_bar_re, "", re.sub(trim_space_re, "", underline)))]
+        align_from_col_idx = {}
+        for col_idx, col in enumerate(cols):
+            if col[0] == ':' and col[-1] == ':':
+                align_from_col_idx[col_idx] = ' style="text-align:center;"'
+            elif col[0] == ':':
+                align_from_col_idx[col_idx] = ' style="text-align:left;"'
+            elif col[-1] == ':':
+                align_from_col_idx[col_idx] = ' style="text-align:right;"'
+
+        # thead
+        hlines = ['<table%s>' % self.md._html_class_str_from_tag('table'), '<thead%s>' % self.md._html_class_str_from_tag('thead'), '<tr>']
+        cols = [re.sub(escape_bar_re, '|', cell.strip()) for cell in re.split(split_bar_re, re.sub(trim_bar_re, "", re.sub(trim_space_re, "", head)))]
+        for col_idx, col in enumerate(cols):
+            hlines.append('  <th%s>%s</th>' % (
+                align_from_col_idx.get(col_idx, ''),
+                self.md._run_span_gamut(col)
+            ))
+        hlines.append('</tr>')
+        hlines.append('</thead>')
+
+        # tbody
+        hlines.append('<tbody>')
+        for line in body.strip('\n').split('\n'):
+            hlines.append('<tr>')
+            cols = [re.sub(escape_bar_re, '|', cell.strip()) for cell in re.split(split_bar_re, re.sub(trim_bar_re, "", re.sub(trim_space_re, "", line)))]
+            for col_idx, col in enumerate(cols):
+                hlines.append('  <td%s>%s</td>' % (
+                    align_from_col_idx.get(col_idx, ''),
+                    self.md._run_span_gamut(col)
+                ))
+            hlines.append('</tr>')
+        hlines.append('</tbody>')
+        hlines.append('</table>')
+
+        return '\n'.join(hlines) + '\n'
+
+    def test(self, text):
+        return True
+
+
+class TelegramSpoiler(Extra):
+    name = 'tg-spoiler'
+    order = (), (Stage.ITALIC_AND_BOLD,)
+
+    _tg_spoiler_re = re.compile(r"\|\|\s?(.+?)\s?\|\|", re.S)
+
+    def run(self, text):
+        return self._tg_spoiler_re.sub(r"<tg-spoiler>\1</tg-spoiler>", text)
+
+    def test(self, text):
+        return '||' in text
+
+
+class Underline(Extra):
+    '''
+    Text inside of double dash is --underlined--.
+    '''
+    name = 'underline'
+    order = (Stage.ITALIC_AND_BOLD,), ()
+
+    _underline_re = re.compile(r"(?<!<!)--(?!>)(?=\S)(.+?)(?<=\S)(?<!<!)--(?!>)", re.S)
+
+    def run(self, text):
+        return self._underline_re.sub(r"<u>\1</u>", text)
+
+    def test(self, text):
+        return '--' in text
+
+
+class Wavedrom(Extra):
+    '''
+    Support for generating Wavedrom digital timing diagrams
+    '''
+    name = 'wavedrom'
+    order = (Stage.CODE_BLOCKS, FencedCodeBlocks), ()
+
+    def test(self, text):
+        match = FencedCodeBlocks.fenced_code_block_re.search(text)
+        return match is None or match.group(2) == 'wavedrom'
+
+    def sub(self, match):
+        # dedent the block for processing
+        lead_indent, waves = self.md._uniform_outdent(match.group(3))
+        # default tags to wrap the wavedrom block in
+        open_tag, close_tag = '<script type="WaveDrom">\n', '</script>'
+
+        # check if the user would prefer to have the SVG embedded directly
+        embed_svg = self.options.get('prefer_embed_svg', True)
+
+        if embed_svg:
+            try:
+                import wavedrom
+                waves = wavedrom.render(waves).tostring()
+                open_tag, close_tag = '<div>', '\n</div>'
+            except ImportError:
+                pass
+
+        # hash SVG to prevent <> chars being messed with
+        self.md._escape_table[waves] = _hash_text(waves)
+
+        return self.md._uniform_indent(
+            '\n%s%s%s\n' % (open_tag, self.md._escape_table[waves], close_tag),
+            lead_indent, include_empty_lines=True
+        )
+
+    def run(self, text):
+        return FencedCodeBlocks.fenced_code_block_re.sub(self.sub, text)
+
+
+class WikiTables(Extra):
+    '''
+    Google Code Wiki-style tables. See
+    <http://code.google.com/p/support/wiki/WikiSyntax#Tables>.
+    '''
+    name = 'wiki-tables'
+    order = (Tables,), ()
+
+    def run(self, text):
+        less_than_tab = self.md.tab_width - 1
+        wiki_table_re = re.compile(r'''
+            (?:(?<=\n\n)|\A\n?)            # leading blank line
+            ^([ ]{0,%d})\|\|.+?\|\|[ ]*\n  # first line
+            (^\1\|\|.+?\|\|\n)*        # any number of subsequent lines
+            ''' % less_than_tab, re.M | re.X)
+        return wiki_table_re.sub(self.sub, text)
+
+    def sub(self, match):
+        ttext = match.group(0).strip()
+        rows = []
+        for line in ttext.splitlines(0):
+            line = line.strip()[2:-2].strip()
+            row = [c.strip() for c in re.split(r'(?<!\\)\|\|', line)]
+            rows.append(row)
+
+        hlines = []
+
+        def add_hline(line, indents=0):
+            hlines.append((self.md.tab * indents) + line)
+
+        def format_cell(text):
+            return self.md._run_span_gamut(re.sub(r"^\s*~", "", cell).strip(" "))
+
+        add_hline('<table%s>' % self.md._html_class_str_from_tag('table'))
+        # Check if first cell of first row is a header cell. If so, assume the whole row is a header row.
+        if rows and rows[0] and re.match(r"^\s*~", rows[0][0]):
+            add_hline('<thead%s>' % self.md._html_class_str_from_tag('thead'), 1)
+            add_hline('<tr>', 2)
+            for cell in rows[0]:
+                add_hline("<th>{}</th>".format(format_cell(cell)), 3)
+            add_hline('</tr>', 2)
+            add_hline('</thead>', 1)
+            # Only one header row allowed.
+            rows = rows[1:]
+        # If no more rows, don't create a tbody.
+        if rows:
+            add_hline('<tbody>', 1)
+            for row in rows:
+                add_hline('<tr>', 2)
+                for cell in row:
+                    add_hline('<td>{}</td>'.format(format_cell(cell)), 3)
+                add_hline('</tr>', 2)
+            add_hline('</tbody>', 1)
+        add_hline('</table>')
+        return '\n'.join(hlines) + '\n'
+
+    def test(self, text):
+        return '||' in text
+
+
+# Register extras
+Admonitions.register()
+Breaks.register()
+CodeFriendly.register()
+FencedCodeBlocks.register()
+Latex.register()
+LinkPatterns.register()
+MarkdownInHTML.register()
+MiddleWordEm.register()
+Mermaid.register()
+Numbering.register()
+PyShell.register()
+SmartyPants.register()
+Strike.register()
+Tables.register()
+TelegramSpoiler.register()
+Underline.register()
+Wavedrom.register()
+WikiTables.register()
+
+
+# ----------------------------------------------------------
+
+
+# ---- internal support functions
+
+
+def calculate_toc_html(toc):
+    """Return the HTML for the current TOC.
+
+    This expects the `_toc` attribute to have been set on this instance.
+    """
+    if toc is None:
+        return None
+
+    def indent():
+        return '  ' * (len(h_stack) - 1)
+    lines = []
+    h_stack = [0]   # stack of header-level numbers
+    for level, id, name in toc:
+        if level > h_stack[-1]:
+            lines.append("%s<ul>" % indent())
+            h_stack.append(level)
+        elif level == h_stack[-1]:
+            lines[-1] += "</li>"
+        else:
+            while level < h_stack[-1]:
+                h_stack.pop()
+                if not lines[-1].endswith("</li>"):
+                    lines[-1] += "</li>"
+                lines.append("%s</ul></li>" % indent())
+        lines.append('%s<li><a href="#%s">%s</a>' % (
+            indent(), id, name))
+    while len(h_stack) > 1:
+        h_stack.pop()
+        if not lines[-1].endswith("</li>"):
+            lines[-1] += "</li>"
+        lines.append("%s</ul>" % indent())
+    return '\n'.join(lines) + '\n'
+
+
+class UnicodeWithAttrs(str):
+    """A subclass of unicode used for the return value of conversion to
+    possibly attach some attributes. E.g. the "toc_html" attribute when
+    the "toc" extra is used.
+    """
+    metadata = None
+    toc_html = None
+
+## {{{ http://code.activestate.com/recipes/577257/ (r1)
+_slugify_strip_re = re.compile(r'[^\w\s-]')
+_slugify_hyphenate_re = re.compile(r'[-\s]+')
+def _slugify(value):
+    """
+    Normalizes string, converts to lowercase, removes non-alpha characters,
+    and converts spaces to hyphens.
+
+    From Django's "django/template/defaultfilters.py".
+    """
+    import unicodedata
+    value = unicodedata.normalize('NFKD', value).encode('utf-8', 'ignore').decode()
+    value = _slugify_strip_re.sub('', value).strip().lower()
+    return _slugify_hyphenate_re.sub('-', value)
+## end of http://code.activestate.com/recipes/577257/ }}}
+
+
+# From http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/52549
+def _curry(*args, **kwargs):
+    function, args = args[0], args[1:]
+    def result(*rest, **kwrest):
+        combined = kwargs.copy()
+        combined.update(kwrest)
+        return function(*args + rest, **combined)
+    return result
+
+
+# Recipe: regex_from_encoded_pattern (1.0)
+def _regex_from_encoded_pattern(s):
+    """'foo'    -> re.compile(re.escape('foo'))
+       '/foo/'  -> re.compile('foo')
+       '/foo/i' -> re.compile('foo', re.I)
+    """
+    if s.startswith('/') and s.rfind('/') != 0:
+        # Parse it: /PATTERN/FLAGS
+        idx = s.rfind('/')
+        _, flags_str = s[1:idx], s[idx+1:]
+        flag_from_char = {
+            "i": re.IGNORECASE,
+            "l": re.LOCALE,
+            "s": re.DOTALL,
+            "m": re.MULTILINE,
+            "u": re.UNICODE,
+        }
+        flags = 0
+        for char in flags_str:
+            try:
+                flags |= flag_from_char[char]
+            except KeyError:
+                raise ValueError("unsupported regex flag: '%s' in '%s' "
+                                 "(must be one of '%s')"
+                                 % (char, s, ''.join(list(flag_from_char.keys()))))
+        return re.compile(s[1:idx], flags)
+    else:  # not an encoded regex
+        return re.compile(re.escape(s))
+
+
+# Recipe: dedent (0.1.2)
+def _dedentlines(lines, tabsize=8, skip_first_line=False):
+    """_dedentlines(lines, tabsize=8, skip_first_line=False) -> dedented lines
+
+        "lines" is a list of lines to dedent.
+        "tabsize" is the tab width to use for indent width calculations.
+        "skip_first_line" is a boolean indicating if the first line should
+            be skipped for calculating the indent width and for dedenting.
+            This is sometimes useful for docstrings and similar.
+
+    Same as dedent() except operates on a sequence of lines. Note: the
+    lines list is modified **in-place**.
+    """
+    DEBUG = False
+    if DEBUG:
+        print("dedent: dedent(..., tabsize=%d, skip_first_line=%r)"\
+              % (tabsize, skip_first_line))
+    margin = None
+    for i, line in enumerate(lines):
+        if i == 0 and skip_first_line: continue
+        indent = 0
+        for ch in line:
+            if ch == ' ':
+                indent += 1
+            elif ch == '\t':
+                indent += tabsize - (indent % tabsize)
+            elif ch in '\r\n':
+                continue  # skip all-whitespace lines
+            else:
+                break
+        else:
+            continue  # skip all-whitespace lines
+        if DEBUG: print("dedent: indent=%d: %r" % (indent, line))
+        if margin is None:
+            margin = indent
+        else:
+            margin = min(margin, indent)
+    if DEBUG: print("dedent: margin=%r" % margin)
+
+    if margin is not None and margin > 0:
+        for i, line in enumerate(lines):
+            if i == 0 and skip_first_line: continue
+            removed = 0
+            for j, ch in enumerate(line):
+                if ch == ' ':
+                    removed += 1
+                elif ch == '\t':
+                    removed += tabsize - (removed % tabsize)
+                elif ch in '\r\n':
+                    if DEBUG: print("dedent: %r: EOL -> strip up to EOL" % line)
+                    lines[i] = lines[i][j:]
+                    break
+                else:
+                    raise ValueError("unexpected non-whitespace char %r in "
+                                     "line %r while removing %d-space margin"
+                                     % (ch, line, margin))
+                if DEBUG:
+                    print("dedent: %r: %r -> removed %d/%d"\
+                          % (line, ch, removed, margin))
+                if removed == margin:
+                    lines[i] = lines[i][j+1:]
+                    break
+                elif removed > margin:
+                    lines[i] = ' '*(removed-margin) + lines[i][j+1:]
+                    break
+            else:
+                if removed:
+                    lines[i] = lines[i][removed:]
+    return lines
+
+
+def _dedent(text, tabsize=8, skip_first_line=False):
+    """_dedent(text, tabsize=8, skip_first_line=False) -> dedented text
+
+        "text" is the text to dedent.
+        "tabsize" is the tab width to use for indent width calculations.
+        "skip_first_line" is a boolean indicating if the first line should
+            be skipped for calculating the indent width and for dedenting.
+            This is sometimes useful for docstrings and similar.
+
+    textwrap.dedent(s), but don't expand tabs to spaces
+    """
+    lines = text.splitlines(1)
+    _dedentlines(lines, tabsize=tabsize, skip_first_line=skip_first_line)
+    return ''.join(lines)
+
+
+class _memoized(object):
+    """Decorator that caches a function's return value each time it is called.
+    If called later with the same arguments, the cached value is returned, and
+    not re-evaluated.
+
+    http://wiki.python.org/moin/PythonDecoratorLibrary
+    """
+    def __init__(self, func):
+        self.func = func
+        self.cache = {}
+
+    def __call__(self, *args):
+        try:
+            return self.cache[args]
+        except KeyError:
+            self.cache[args] = value = self.func(*args)
+            return value
+        except TypeError:
+            # uncachable -- for instance, passing a list as an argument.
+            # Better to not cache than to blow up entirely.
+            return self.func(*args)
+
+    def __repr__(self):
+        """Return the function's docstring."""
+        return self.func.__doc__
+
+
+def _xml_oneliner_re_from_tab_width(tab_width):
+    """Standalone XML processing instruction regex."""
+    return re.compile(r"""
+        (?:
+            (?<=\n\n)       # Starting after a blank line
+            |               # or
+            \A\n?           # the beginning of the doc
+        )
+        (                           # save in $1
+            [ ]{0,%d}
+            (?:
+                <\?\w+\b\s+.*?\?>   # XML processing instruction
+                |
+                <\w+:\w+\b\s+.*?/>  # namespaced single tag
+            )
+            [ \t]*
+            (?=\n{2,}|\Z)       # followed by a blank line or end of document
+        )
+        """ % (tab_width - 1), re.X)
+_xml_oneliner_re_from_tab_width = _memoized(_xml_oneliner_re_from_tab_width)
+
+
+def _hr_tag_re_from_tab_width(tab_width):
+    return re.compile(r"""
+        (?:
+            (?<=\n\n)       # Starting after a blank line
+            |               # or
+            \A\n?           # the beginning of the doc
+        )
+        (                       # save in \1
+            [ ]{0,%d}
+            <(hr)               # start tag = \2
+            \b                  # word break
+            ([^<>])*?           #
+            /?>                 # the matching end tag
+            [ \t]*
+            (?=\n{2,}|\Z)       # followed by a blank line or end of document
+        )
+        """ % (tab_width - 1), re.X)
+_hr_tag_re_from_tab_width = _memoized(_hr_tag_re_from_tab_width)
+
+
+def _xml_escape_attr(attr, skip_single_quote=True):
+    """Escape the given string for use in an HTML/XML tag attribute.
+
+    By default this doesn't bother with escaping `'` to `&#39;`, presuming that
+    the tag attribute is surrounded by double quotes.
+    """
+    escaped = _AMPERSAND_RE.sub('&amp;', attr)
+
+    escaped = (attr
+        .replace('"', '&quot;')
+        .replace('<', '&lt;')
+        .replace('>', '&gt;'))
+    if not skip_single_quote:
+        escaped = escaped.replace("'", "&#39;")
+    return escaped
+
+
+def _xml_encode_email_char_at_random(ch):
+    r = random()
+    # Roughly 10% raw, 45% hex, 45% dec.
+    # '@' *must* be encoded. I [John Gruber] insist.
+    # Issue 26: '_' must be encoded.
+    if r > 0.9 and ch not in "@_":
+        return ch
+    elif r < 0.45:
+        # The [1:] is to drop leading '0': 0x63 -> x63
+        return '&#%s;' % hex(ord(ch))[1:]
+    else:
+        return '&#%s;' % ord(ch)
+
+
+def _html_escape_url(attr, safe_mode=False, charset=None):
+    """
+    Replace special characters that are potentially malicious in url string.
+
+    Args:
+        charset: don't escape characters from this charset. Currently the only
+            exception is for '+' when charset=='base64'
+    """
+    escaped = (attr
+        .replace('"', '&quot;')
+        .replace('<', '&lt;')
+        .replace('>', '&gt;'))
+    if safe_mode:
+        if charset != 'base64':
+            escaped = escaped.replace('+', ' ')
+        escaped = escaped.replace("'", "&#39;")
+    return escaped
+
+
+# ---- mainline
+
+class _NoReflowFormatter(argparse.RawDescriptionHelpFormatter):
+    """An argparse formatter that does NOT reflow the description."""
+    def format_description(self, description):
+        return description or ""
+
+
+def _test():
+    import doctest
+    doctest.testmod()
+
+
+def main(argv=None):
+    if argv is None:
+        argv = sys.argv
+    if not logging.root.handlers:
+        logging.basicConfig()
+
+    parser = argparse.ArgumentParser(
+        prog="markdown2", description=cmdln_desc, usage='%(prog)s [PATHS...]',
+        formatter_class=_NoReflowFormatter
+    )
+    parser.add_argument('--version', action='version',
+                        version='%(prog)s {version}'.format(version=__version__))
+    parser.add_argument('paths', nargs='*',
+                        help=(
+                            'optional list of files to convert.'
+                            'If none are given, stdin will be used'
+                        ))
+    parser.add_argument("-v", "--verbose", dest="log_level",
+                      action="store_const", const=logging.DEBUG,
+                      help="more verbose output")
+    parser.add_argument("--encoding",
+                      help="specify encoding of text content")
+    parser.add_argument("--html4tags", action="store_true", default=False,
+                      help="use HTML 4 style for empty element tags")
+    parser.add_argument("-s", "--safe", metavar="MODE", dest="safe_mode",
+                      help="sanitize literal HTML: 'escape' escapes "
+                           "HTML meta chars, 'replace' replaces with an "
+                           "[HTML_REMOVED] note")
+    parser.add_argument("-x", "--extras", action="append",
+                      help="Turn on specific extra features (not part of "
+                           "the core Markdown spec). See above.")
+    parser.add_argument("--use-file-vars",
+                      help="Look for and use Emacs-style 'markdown-extras' "
+                           "file var to turn on extras. See "
+                           "<https://github.com/trentm/python-markdown2/wiki/Extras>")
+    parser.add_argument("--link-patterns-file",
+                      help="path to a link pattern file")
+    parser.add_argument("--self-test", action="store_true",
+                      help="run internal self-tests (some doctests)")
+    parser.add_argument("--compare", action="store_true",
+                      help="run against Markdown.pl as well (for testing)")
+    parser.set_defaults(log_level=logging.INFO, compare=False,
+                        encoding="utf-8", safe_mode=None, use_file_vars=False)
+    opts = parser.parse_args()
+    paths = opts.paths
+    log.setLevel(opts.log_level)
+
+    if opts.self_test:
+        return _test()
+
+    if opts.extras:
+        extras = {}
+        for s in opts.extras:
+            splitter = re.compile("[,;: ]+")
+            for e in splitter.split(s):
+                if '=' in e:
+                    ename, earg = e.split('=', 1)
+                    try:
+                        earg = int(earg)
+                    except ValueError:
+                        pass
+                else:
+                    ename, earg = e, None
+                extras[ename] = earg
+    else:
+        extras = None
+
+    if opts.link_patterns_file:
+        link_patterns = []
+        f = open(opts.link_patterns_file)
+        try:
+            for i, line in enumerate(f.readlines()):
+                if not line.strip(): continue
+                if line.lstrip().startswith("#"): continue
+                try:
+                    pat, href = line.rstrip().rsplit(None, 1)
+                except ValueError:
+                    raise MarkdownError("%s:%d: invalid link pattern line: %r"
+                                        % (opts.link_patterns_file, i+1, line))
+                link_patterns.append(
+                    (_regex_from_encoded_pattern(pat), href))
+        finally:
+            f.close()
+    else:
+        link_patterns = None
+
+    from os.path import abspath, dirname, exists, join
+    markdown_pl = join(dirname(dirname(abspath(__file__))), "test",
+                       "Markdown.pl")
+    if not paths:
+        paths = ['-']
+    for path in paths:
+        if path == '-':
+            text = sys.stdin.read()
+        else:
+            fp = codecs.open(path, 'r', opts.encoding)
+            text = fp.read()
+            fp.close()
+        if opts.compare:
+            from subprocess import PIPE, Popen
+            print("==== Markdown.pl ====")
+            p = Popen('perl %s' % markdown_pl, shell=True, stdin=PIPE, stdout=PIPE, close_fds=True)
+            p.stdin.write(text.encode('utf-8'))
+            p.stdin.close()
+            perl_html = p.stdout.read().decode('utf-8')
+            sys.stdout.write(perl_html)
+            print("==== markdown2.py ====")
+        html = markdown(text,
+            html4tags=opts.html4tags,
+            safe_mode=opts.safe_mode,
+            extras=extras, link_patterns=link_patterns,
+            use_file_vars=opts.use_file_vars,
+            cli=True)
+        sys.stdout.write(html)
+        if extras and "toc" in extras:
+            log.debug("toc_html: " +
+                str(html.toc_html.encode(sys.stdout.encoding or "utf-8", 'xmlcharrefreplace')))
+        if opts.compare:
+            test_dir = join(dirname(dirname(abspath(__file__))), "test")
+            if exists(join(test_dir, "test_markdown2.py")):
+                sys.path.insert(0, test_dir)
+                from test_markdown2 import norm_html_from_html
+                norm_html = norm_html_from_html(html)
+                norm_perl_html = norm_html_from_html(perl_html)
+            else:
+                norm_html = html
+                norm_perl_html = perl_html
+            print("==== match? %r ====" % (norm_perl_html == norm_html))
+
+
+if __name__ == "__main__":
+    sys.exit(main(sys.argv))