diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..2cc2704
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,54 @@
+*.py[cod]
+
+test.db
+test.txt
+sina.html
+
+# C extensions
+*.so
+
+# Packages
+*.egg
+*.egg-info
+dist
+build
+eggs
+parts
+bin
+var
+sdist
+develop-eggs
+.installed.cfg
+lib
+lib64
+__pycache__
+
+# Installer logs
+pip-log.txt
+
+# Unit test / coverage reports
+.coverage
+.tox
+nosetests.xml
+
+######################
+# OS generated files #
+######################
+.DS_Store
+.DS_Store?
+._*
+.Spotlight-V100
+.Trashes
+Icon?
+ehthumbs.db
+Thumbs.db
+dist
+MANIFEST
+
+# Translations
+*.mo
+
+# Mr Developer
+.mr.developer.cfg
+.project
+.pydevproject
diff --git a/README.md b/README.md
new file mode 100644
index 0000000..07bf4f6
--- /dev/null
+++ b/README.md
@@ -0,0 +1,4 @@
+awesome-python3-webapp
+======================
+
+A python webapp tutorial.
diff --git a/www/apis.py b/www/apis.py
new file mode 100644
index 0000000..3a6b2c6
--- /dev/null
+++ b/www/apis.py
@@ -0,0 +1,41 @@
+#!/usr/bin/env python3
+# -*- coding: utf-8 -*-
+
+__author__ = 'Michael Liao'
+
+'''
+JSON API definition.
+'''
+
+import json, logging, inspect, functools
+
+class APIError(Exception):
+    '''
+    the base APIError which contains error(required), data(optional) and message(optional).
+    '''
+    def __init__(self, error, data='', message=''):
+        super(APIError, self).__init__(message)
+        self.error = error
+        self.data = data
+        self.message = message
+
+class APIValueError(APIError):
+    '''
+    Indicate the input value has error or invalid. The data specifies the error field of input form.
+    '''
+    def __init__(self, field, message=''):
+        super(APIValueError, self).__init__('value:invalid', field, message)
+
+class APIResourceNotFoundError(APIError):
+    '''
+    Indicate the resource was not found. The data specifies the resource name.
+    '''
+    def __init__(self, field, message=''):
+        super(APIResourceNotFoundError, self).__init__('value:notfound', field, message)
+
+class APIPermissionError(APIError):
+    '''
+    Indicate the api has no permission.
+    '''
+    def __init__(self, message=''):
+        super(APIPermissionError, self).__init__('permission:forbidden', 'permission', message)
diff --git a/www/app.py b/www/app.py
new file mode 100755
index 0000000..50e94cd
--- /dev/null
+++ b/www/app.py
@@ -0,0 +1,126 @@
+#!/usr/bin/env python3
+# -*- coding: utf-8 -*-
+
+__author__ = 'Michael Liao'
+
+'''
+async web application.
+'''
+
+import logging; logging.basicConfig(level=logging.INFO)
+
+import asyncio, os, json, time
+from datetime import datetime
+
+from aiohttp import web
+from jinja2 import Environment, FileSystemLoader
+
+import orm
+from coroweb import add_routes, add_static
+
+def init_jinja2(app, **kw):
+    logging.info('init jinja2...')
+    options = dict(
+        autoescape = kw.get('autoescape', True),
+        block_start_string = kw.get('block_start_string', '{%'),
+        block_end_string = kw.get('block_end_string', '%}'),
+        variable_start_string = kw.get('variable_start_string', '{{'),
+        variable_end_string = kw.get('variable_end_string', '}}'),
+        auto_reload = kw.get('auto_reload', True)
+    )
+    path = kw.get('path', None)
+    if path is None:
+        path = os.path.join(os.path.dirname(os.path.abspath(__file__)), 'templates')
+    logging.info('set jinja2 template path: %s' % path)
+    env = Environment(loader=FileSystemLoader(path), **options)
+    filters = kw.get('filters', None)
+    if filters is not None:
+        for name, f in filters.items():
+            env.filters[name] = f
+    app['__templating__'] = env
+
+async def logger_factory(app, handler):
+    async def logger(request):
+        logging.info('Request: %s %s' % (request.method, request.path))
+        # await asyncio.sleep(0.3)
+        return (await handler(request))
+    return logger
+
+async def data_factory(app, handler):
+    async def parse_data(request):
+        if request.method == 'POST':
+            if request.content_type.startswith('application/json'):
+                request.__data__ = await request.json()
+                logging.info('request json: %s' % str(request.__data__))
+            elif request.content_type.startswith('application/x-www-form-urlencoded'):
+                request.__data__ = await request.post()
+                logging.info('request form: %s' % str(request.__data__))
+        return (await handler(request))
+    return parse_data
+
+async def response_factory(app, handler):
+    async def response(request):
+        logging.info('Response handler...')
+        r = await handler(request)
+        if isinstance(r, web.StreamResponse):
+            return r
+        if isinstance(r, bytes):
+            resp = web.Response(body=r)
+            resp.content_type = 'application/octet-stream'
+            return resp
+        if isinstance(r, str):
+            if r.startswith('redirect:'):
+                return web.HTTPFound(r[9:])
+            resp = web.Response(body=r.encode('utf-8'))
+            resp.content_type = 'text/html;charset=utf-8'
+            return resp
+        if isinstance(r, dict):
+            template = r.get('__template__')
+            if template is None:
+                resp = web.Response(body=json.dumps(r, ensure_ascii=False, default=lambda o: o.__dict__).encode('utf-8'))
+                resp.content_type = 'application/json;charset=utf-8'
+                return resp
+            else:
+                resp = web.Response(body=app['__templating__'].get_template(template).render(**r).encode('utf-8'))
+                resp.content_type = 'text/html;charset=utf-8'
+                return resp
+        if isinstance(r, int) and r >= 100 and r < 600:
+            return web.Response(r)
+        if isinstance(r, tuple) and len(r) == 2:
+            t, m = r
+            if isinstance(t, int) and t >= 100 and t < 600:
+                return web.Response(t, str(m))
+        # default:
+        resp = web.Response(body=str(r).encode('utf-8'))
+        resp.content_type = 'text/plain;charset=utf-8'
+        return resp
+    return response
+
+def datetime_filter(t):
+    delta = int(time.time() - t)
+    if delta < 60:
+        return u'1分钟前'
+    if delta < 3600:
+        return u'%s分钟前' % (delta // 60)
+    if delta < 86400:
+        return u'%s小时前' % (delta // 3600)
+    if delta < 604800:
+        return u'%s天前' % (delta // 86400)
+    dt = datetime.fromtimestamp(t)
+    return u'%s年%s月%s日' % (dt.year, dt.month, dt.day)
+
+async def init(loop):
+    await orm.create_pool(loop=loop, host='127.0.0.1', port=3306, user='www', password='www', db='awesome')
+    app = web.Application(loop=loop, middlewares=[
+        logger_factory, response_factory
+    ])
+    init_jinja2(app, filters=dict(datetime=datetime_filter))
+    add_routes(app, 'handlers')
+    add_static(app)
+    srv = await loop.create_server(app.make_handler(), '127.0.0.1', 9000)
+    logging.info('server started at http://127.0.0.1:9000...')
+    return srv
+
+loop = asyncio.get_event_loop()
+loop.run_until_complete(init(loop))
+loop.run_forever()
diff --git a/www/coroweb.py b/www/coroweb.py
new file mode 100644
index 0000000..40c52ea
--- /dev/null
+++ b/www/coroweb.py
@@ -0,0 +1,173 @@
+#!/usr/bin/env python3
+# -*- coding: utf-8 -*-
+
+__author__ = 'Michael Liao'
+
+import asyncio, os, inspect, logging, functools
+
+from urllib import parse
+
+from aiohttp import web
+
+from apis import APIError
+
+def get(path):
+    '''
+    Define decorator @get('/path')
+    '''
+    def decorator(func):
+        @functools.wraps(func)
+        def wrapper(*args, **kw):
+            return func(*args, **kw)
+        wrapper.__method__ = 'GET'
+        wrapper.__route__ = path
+        return wrapper
+    return decorator
+
+def post(path):
+    '''
+    Define decorator @post('/path')
+    '''
+    def decorator(func):
+        @functools.wraps(func)
+        def wrapper(*args, **kw):
+            return func(*args, **kw)
+        wrapper.__method__ = 'POST'
+        wrapper.__route__ = path
+        return wrapper
+    return decorator
+
+def get_required_kw_args(fn):
+    args = []
+    params = inspect.signature(fn).parameters
+    for name, param in params.items():
+        if param.kind == inspect.Parameter.KEYWORD_ONLY and param.default == inspect.Parameter.empty:
+            args.append(name)
+    return tuple(args)
+
+def get_named_kw_args(fn):
+    args = []
+    params = inspect.signature(fn).parameters
+    for name, param in params.items():
+        if param.kind == inspect.Parameter.KEYWORD_ONLY:
+            args.append(name)
+    return tuple(args)
+
+def has_named_kw_args(fn):
+    params = inspect.signature(fn).parameters
+    for name, param in params.items():
+        if param.kind == inspect.Parameter.KEYWORD_ONLY:
+            return True
+
+def has_var_kw_arg(fn):
+    params = inspect.signature(fn).parameters
+    for name, param in params.items():
+        if param.kind == inspect.Parameter.VAR_KEYWORD:
+            return True
+
+def has_request_arg(fn):
+    sig = inspect.signature(fn)
+    params = sig.parameters
+    found = False
+    for name, param in params.items():
+        if name == 'request':
+            found = True
+            continue
+        if found and (param.kind != inspect.Parameter.VAR_POSITIONAL and param.kind != inspect.Parameter.KEYWORD_ONLY and param.kind != inspect.Parameter.VAR_KEYWORD):
+            raise ValueError('request parameter must be the last named parameter in function: %s%s' % (fn.__name__, str(sig)))
+    return found
+
+class RequestHandler(object):
+
+    def __init__(self, app, fn):
+        self._app = app
+        self._func = fn
+        self._has_request_arg = has_request_arg(fn)
+        self._has_var_kw_arg = has_var_kw_arg(fn)
+        self._has_named_kw_args = has_named_kw_args(fn)
+        self._named_kw_args = get_named_kw_args(fn)
+        self._required_kw_args = get_required_kw_args(fn)
+
+    async def __call__(self, request):
+        kw = None
+        if self._has_var_kw_arg or self._has_named_kw_args or self._required_kw_args:
+            if request.method == 'POST':
+                if not request.content_type:
+                    return web.HTTPBadRequest('Missing Content-Type.')
+                ct = request.content_type.lower()
+                if ct.startswith('application/json'):
+                    params = await request.json()
+                    if not isinstance(params, dict):
+                        return web.HTTPBadRequest('JSON body must be object.')
+                    kw = params
+                elif ct.startswith('application/x-www-form-urlencoded') or ct.startswith('multipart/form-data'):
+                    params = await request.post()
+                    kw = dict(**params)
+                else:
+                    return web.HTTPBadRequest('Unsupported Content-Type: %s' % request.content_type)
+            if request.method == 'GET':
+                qs = request.query_string
+                if qs:
+                    kw = dict()
+                    for k, v in parse.parse_qs(qs, True).items():
+                        kw[k] = v[0]
+        if kw is None:
+            kw = dict(**request.match_info)
+        else:
+            if not self._has_var_kw_arg and self._named_kw_args:
+                # remove all unamed kw:
+                copy = dict()
+                for name in self._named_kw_args:
+                    if name in kw:
+                        copy[name] = kw[name]
+                kw = copy
+            # check named arg:
+            for k, v in request.match_info.items():
+                if k in kw:
+                    logging.warning('Duplicate arg name in named arg and kw args: %s' % k)
+                kw[k] = v
+        if self._has_request_arg:
+            kw['request'] = request
+        # check required kw:
+        if self._required_kw_args:
+            for name in self._required_kw_args:
+                if not name in kw:
+                    return web.HTTPBadRequest('Missing argument: %s' % name)
+        logging.info('call with args: %s' % str(kw))
+        try:
+            r = await self._func(**kw)
+            return r
+        except APIError as e:
+            return dict(error=e.error, data=e.data, message=e.message)
+
+def add_static(app):
+    path = os.path.join(os.path.dirname(os.path.abspath(__file__)), 'static')
+    app.router.add_static('/static/', path)
+    logging.info('add static %s => %s' % ('/static/', path))
+
+def add_route(app, fn):
+    method = getattr(fn, '__method__', None)
+    path = getattr(fn, '__route__', None)
+    if path is None or method is None:
+        raise ValueError('@get or @post not defined in %s.' % str(fn))
+    if not asyncio.iscoroutinefunction(fn) and not inspect.isgeneratorfunction(fn):
+        fn = asyncio.coroutine(fn)
+    logging.info('add route %s %s => %s(%s)' % (method, path, fn.__name__, ', '.join(inspect.signature(fn).parameters.keys())))
+    app.router.add_route(method, path, RequestHandler(app, fn))
+
+def add_routes(app, module_name):
+    n = module_name.rfind('.')
+    if n == (-1):
+        mod = __import__(module_name, globals(), locals())
+    else:
+        name = module_name[n+1:]
+        mod = getattr(__import__(module_name[:n], globals(), locals(), [name]), name)
+    for attr in dir(mod):
+        if attr.startswith('_'):
+            continue
+        fn = getattr(mod, attr)
+        if callable(fn):
+            method = getattr(fn, '__method__', None)
+            path = getattr(fn, '__route__', None)
+            if method and path:
+                add_route(app, fn)
diff --git a/www/favicon.ico b/www/favicon.ico
new file mode 100644
index 0000000..5f9ba4a
Binary files /dev/null and b/www/favicon.ico differ
diff --git a/www/handlers.py b/www/handlers.py
new file mode 100644
index 0000000..e668764
--- /dev/null
+++ b/www/handlers.py
@@ -0,0 +1,6 @@
+#!/usr/bin/env python3
+# -*- coding: utf-8 -*-
+
+__author__ = 'Michael Liao'
+
+' url handlers '
diff --git a/www/markdown2.py b/www/markdown2.py
new file mode 100755
index 0000000..31c0ae9
--- /dev/null
+++ b/www/markdown2.py
@@ -0,0 +1,2440 @@
+#!/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)
+
+from __future__ import generators
+
+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):
+
+* 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.
+* html-classes: Takes a dict mapping html tag names (lowercase) to a
+  string to use for a "class" tag attribute. Currently only supports
+  "pre" and "code" tags. Add an issue if you require this for other tags.
+* 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.
+* nofollow: Add `rel="nofollow"` to add `<a>` tags with an href. See
+  <http://en.wikipedia.org/wiki/Nofollow>.
+* pyshell: Treats unindented Python interactive shell sessions as <code>
+  blocks.
+* link-patterns: Auto-link given regex patterns in text (e.g. bug number
+  references, revision number references).
+* smarty-pants: Replaces ' and " with curly quotation marks or curly
+  apostrophes.  Replaces --, ---, ..., and . . . with en dashes, em dashes,
+  and ellipses.
+* toc: The returned HTML string gets a new "toc_html" attribute which is
+  a Table of Contents for the document. (experimental)
+* xml: Passes one-liner processing instructions and namespaced XML tags.
+* 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>.
+* wiki-tables: Google Code Wiki-style tables. See
+  <http://code.google.com/p/support/wiki/WikiSyntax#Tables>.
+"""
+
+# 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, 3, 0)
+__version__ = '.'.join(map(str, __version_info__))
+__author__ = "Trent Mick"
+
+import os
+import sys
+from pprint import pprint, pformat
+import re
+import logging
+try:
+    from hashlib import md5
+except ImportError:
+    from md5 import md5
+import optparse
+from random import random, randint
+import codecs
+
+
+#---- Python version compat
+
+try:
+    from urllib.parse import quote # python3
+except ImportError:
+    from urllib import quote # python2
+
+if sys.version_info[:2] < (2,4):
+    from sets import Set as set
+    def reversed(sequence):
+        for i in sequence[::-1]:
+            yield i
+
+# Use `bytes` for byte strings and `unicode` for unicode strings (str in Py3).
+if sys.version_info[0] <= 2:
+    py3 = False
+    try:
+        bytes
+    except NameError:
+        bytes = str
+    base_string_type = basestring
+elif sys.version_info[0] >= 3:
+    py3 = True
+    unicode = str
+    base_string_type = str
+
+
+
+#---- globals
+
+DEBUG = False
+log = logging.getLogger("markdown")
+
+DEFAULT_TAB_WIDTH = 4
+
+
+SECRET_SALT = bytes(randint(0, 1000000))
+def _hash_text(s):
+    return 'md5-' + md5(SECRET_SALT + s.encode("utf-8")).hexdigest()
+
+# Table of hash values for escaped characters:
+g_escape_table = dict([(ch, _hash_text(ch))
+    for ch in '\\`*_{}[]()>#+-.!'])
+
+
+
+#---- 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,
+                  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,
+                    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,
+             use_file_vars=False):
+    return Markdown(html4tags=html4tags, tab_width=tab_width,
+                    safe_mode=safe_mode, extras=extras,
+                    link_patterns=link_patterns,
+                    use_file_vars=use_file_vars).convert(text)
+
+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
+
+    urls = None
+    titles = None
+    html_blocks = None
+    html_spans = None
+    html_removed_text = "[HTML_REMOVED]"  # for compat with markdown.py
+
+    # Used to track when we're inside an ordered or unordered list
+    # (see _ProcessListItems() for details):
+    list_level = 0
+
+    _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, use_file_vars=False):
+        if html4tags:
+            self.empty_element_suffix = ">"
+        else:
+            self.empty_element_suffix = " />"
+        self.tab_width = 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 and not "header-ids" in self.extras:
+            self.extras["header-ids"] = None   # "toc" implies "header-ids"
+        self._instance_extras = self.extras.copy()
+
+        self.link_patterns = link_patterns
+        self.use_file_vars = use_file_vars
+        self._outdent_re = re.compile(r'^(\t|[ ]{1,%d})' % tab_width, re.M)
+
+        self._escape_table = g_escape_table.copy()
+        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()
+        if "footnotes" in self.extras:
+            self.footnotes = {}
+            self.footnote_ids = []
+        if "header-ids" in self.extras:
+            self._count_from_header_id = {} # no `defaultdict` in Python 2.4
+        if "metadata" in self.extras:
+            self.metadata = {}
+
+    # Per <https://developer.mozilla.org/en-US/docs/HTML/Element/a> "rel"
+    # should only be used in <a> tags with an "href" attribute.
+    _a_nofollow = re.compile(r"<(a)([^>]*href=)", re.IGNORECASE)
+
+    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, unicode):
+            #TODO: perhaps shouldn't presume UTF-8 for string input?
+            text = unicode(text, 'utf-8')
+
+        if self.use_file_vars:
+            # Look for emacs-style file variable hints.
+            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
+
+        # Standardize line endings:
+        text = re.sub("\r\n|\r", "\n", text)
+
+        # 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 "fenced-code-blocks" in self.extras and not self.safe_mode:
+            text = self._do_fenced_code_blocks(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)
+
+        if "fenced-code-blocks" in self.extras and self.safe_mode:
+            text = self._do_fenced_code_blocks(text)
+
+        # 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)
+
+        if "nofollow" in self.extras:
+            text = self._a_nofollow.sub(r'<\1 rel="nofollow"\2', text)
+
+        text += "\n"
+
+        rv = UnicodeWithAttrs(text)
+        if "toc" in self.extras:
+            rv._toc = self._toc
+        if "metadata" in self.extras:
+            rv.metadata = self.metadata
+        return rv
+
+    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
+
+    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 '---'-fenced `key: value`
+    # pairs. E.g. (indented for presentation):
+    #   ---
+    #   foo: bar
+    #   another-var: blah blah
+    #   ---
+    _metadata_pat = re.compile("""^---[ \t]*\n((?:[ \t]*[^ \t:]+[ \t]*:[^\n]*\n)+)---[ \t]*\n""")
+
+    def _extract_metadata(self, text):
+        # fast test
+        if not text.startswith("---"):
+            return text
+        match = self._metadata_pat.match(text)
+        if not match:
+            return text
+
+        tail = text[len(match.group(0)):]
+        metadata_str = match.group(1).strip()
+        for line in metadata_str.split('\n'):
+            key, value = line.split(':', 1)
+            self.metadata[key.strip()] = value.strip()
+
+        return tail
+
+
+    _emacs_oneliner_vars_pat = re.compile(r"-\*-\s*([^\r\n]*?)\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 _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(1)
+                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
+
+    # Cribbed from a post by Bart Lateur:
+    # <http://www.nntp.perl.org/group/perl.macperl.anyperl/154>
+    _detab_re = re.compile(r'(.*?)\t', re.M)
+    def _detab_sub(self, match):
+        g1 = match.group(1)
+        return g1 + (' ' * (self.tab_width - len(g1) % self.tab_width))
+    def _detab(self, text):
+        r"""Remove (leading?) tabs from a file.
+
+            >>> 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
+        return self._detab_re.subn(self._detab_sub, text)[0]
+
+    # 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'
+    _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
+
+    _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):
+        html = match.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')
+                middle = '\n'.join(lines[1:-1])
+                last_line = lines[-1]
+                first_line = first_line[:m.start()] + first_line[m.end():]
+                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"])
+        key = _hash_text(html)
+        self.html_blocks[key] = html
+        return "\n\n" + key + "\n\n"
+
+    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_re.sub(hash_html_block_sub, text)
+
+        # Now match more liberally, simply from `\n<tag>` to `</tag>\n`
+        text = self._liberal_tag_block_re.sub(hash_html_block_sub, text)
+
+        # 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 _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}){3,}$', re.M)
+
+    def _run_block_gamut(self, text):
+        # These are all the transformations that form block-level
+        # tags like paragraphs, headers, and list items.
+
+        if "fenced-code-blocks" in self.extras:
+            text = self._do_fenced_code_blocks(text)
+
+        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)
+
+        if "pyshell" in self.extras:
+            text = self._prepare_pyshell_blocks(text)
+        if "wiki-tables" in self.extras:
+            text = self._do_wiki_tables(text)
+        if "tables" in self.extras:
+            text = self._do_tables(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
+
+    def _pyshell_block_sub(self, match):
+        lines = match.group(0).splitlines(0)
+        _dedentlines(lines)
+        indent = ' ' * self.tab_width
+        s = ('\n' # separate from possible cuddled paragraph
+             + indent + ('\n'+indent).join(lines)
+             + '\n\n')
+        return s
+
+    def _prepare_pyshell_blocks(self, text):
+        """Ensure that Python interactive shell sessions are put in
+        code blocks -- even if not properly indented.
+        """
+        if ">>>" not in text:
+            return text
+
+        less_than_tab = self.tab_width - 1
+        _pyshell_block_re = re.compile(r"""
+            ^([ ]{0,%d})>>>[ ].*\n   # first line
+            ^(\1.*\S+.*\n)*         # any number of subsequent lines
+            ^\n                     # ends with a blank line
+            """ % less_than_tab, re.M | re.X)
+
+        return _pyshell_block_re.sub(self._pyshell_block_sub, text)
+
+    def _table_sub(self, match):
+        head, underline, body = match.groups()
+
+        # Determine aligns for columns.
+        cols = [cell.strip() for cell in underline.strip('| \t\n').split('|')]
+        align_from_col_idx = {}
+        for col_idx, col in enumerate(cols):
+            if col[0] == ':' and col[-1] == ':':
+                align_from_col_idx[col_idx] = ' align="center"'
+            elif col[0] == ':':
+                align_from_col_idx[col_idx] = ' align="left"'
+            elif col[-1] == ':':
+                align_from_col_idx[col_idx] = ' align="right"'
+
+        # thead
+        hlines = ['<table>', '<thead>', '<tr>']
+        cols = [cell.strip() for cell in head.strip('| \t\n').split('|')]
+        for col_idx, col in enumerate(cols):
+            hlines.append('  <th%s>%s</th>' % (
+                align_from_col_idx.get(col_idx, ''),
+                self._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 = [cell.strip() for cell in line.strip('| \t\n').split('|')]
+            for col_idx, col in enumerate(cols):
+                hlines.append('  <td%s>%s</td>' % (
+                    align_from_col_idx.get(col_idx, ''),
+                    self._run_span_gamut(col)
+                ))
+            hlines.append('</tr>')
+        hlines.append('</tbody>')
+        hlines.append('</table>')
+
+        return '\n'.join(hlines) + '\n'
+
+    def _do_tables(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.tab_width - 1
+        table_re = re.compile(r'''
+                (?:(?<=\n\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
+                    (?:  \|\ *:?-+:?\ *  )+  \|?  \n
+                    |
+                    # or, underline row without leading bar
+                    (?:  \ *:?-+:?\ *\|  )+  (?:  \ *:?-+:?\ *  )?  \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._table_sub, text)
+
+    def _wiki_table_sub(self, match):
+        ttext = match.group(0).strip()
+        #print 'wiki table: %r' % match.group(0)
+        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)
+        #pprint(rows)
+        hlines = ['<table>', '<tbody>']
+        for row in rows:
+            hrow = ['<tr>']
+            for cell in row:
+                hrow.append('<td>')
+                hrow.append(self._run_span_gamut(cell))
+                hrow.append('</td>')
+            hrow.append('</tr>')
+            hlines.append(''.join(hrow))
+        hlines += ['</tbody>', '</table>']
+        return '\n'.join(hlines) + '\n'
+
+    def _do_wiki_tables(self, text):
+        # Optimization.
+        if "||" not in text:
+            return text
+
+        less_than_tab = self.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._wiki_table_sub, text)
+
+    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)
+
+        if "link-patterns" in self.extras:
+            text = self._do_link_patterns(text)
+
+        text = self._encode_amps_and_angles(text)
+
+        text = self._do_italics_and_bold(text)
+
+        if "smarty-pants" in self.extras:
+            text = self._do_smart_punctuation(text)
+
+        # Do hard breaks:
+        if "break-on-newline" in self.extras:
+            text = re.sub(r" *\n", "<br%s\n" % self.empty_element_suffix, text)
+        else:
+            text = re.sub(r" {2,}\n", " <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"""
+        (
+            # tag
+            </?
+            (?:\w+)                                     # tag name
+            (?:\s+(?:[\w-]+:)?[\w-]+=(?:".*?"|'.*?'))*  # attributes
+            \s*/?>
+            |
+            # auto-link (e.g., <http://www.activestate.com/>)
+            <\w+[^>]*>
+            |
+            <!--.*?-->      # comment
+            |
+            <\?.*?\?>       # processing instruction
+        )
+        """, re.X)
+
+    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.
+        escaped = []
+        is_html_markup = False
+        for token in self._sorta_html_tokenize_re.split(text):
+            if is_html_markup:
+                # 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.
+                escaped.append(token.replace('*', self._escape_table['*'])
+                                    .replace('_', self._escape_table['_']))
+            else:
+                escaped.append(self._encode_backslash_escapes(token))
+            is_html_markup = not is_html_markup
+        return ''.join(escaped)
+
+    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
+
+        tokens = []
+        is_html_markup = False
+        for token in self._sorta_html_tokenize_re.split(text):
+            if is_html_markup and not _is_auto_link(token):
+                sanitized = self._sanitize_html(token)
+                key = _hash_text(sanitized)
+                self.html_spans[key] = sanitized
+                tokens.append(key)
+            else:
+                tokens.append(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
+
+    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]
+
+            # 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
+            if p == text_length:
+                return text
+
+            # Inline anchor or img?
+            if text[p] == '(': # 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' \
+                            % (url.replace('"', '&quot;'),
+                               _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[url_end_idx:]
+                    elif start_idx >= anchor_allowed_pos:
+                        result_head = '<a href="%s"%s>' % (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:
+                            before = 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' \
+                                % (url.replace('"', '&quot;'),
+                                   link_text.replace('"', '&quot;'),
+                                   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:
+                            result = '<a href="%s"%s>%s</a>' \
+                                % (url, title_str, link_text)
+                            result_head = '<a href="%s"%s>' % (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.
+                        curr_pos = match.end()
+                    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, base_string_type):
+            header_id = prefix + '-' + header_id
+        if header_id in self._count_from_header_id:
+            self._count_from_header_id[header_id] += 1
+            header_id += '-%s' % self._count_from_header_id[header_id]
+        else:
+            self._count_from_header_id[header_id] = 1
+        return header_id
+
+    _toc = None
+    def _toc_add_entry(self, level, id, name):
+        if self._toc is None:
+            self._toc = []
+        self._toc.append((level, id, self._unescape_special_chars(name)))
+
+    _h_re_base = r'''
+        (^(.+)[ \t]*\n(=+|-+)[ \t]*\n+)
+        |
+        (^(\#{1,6})  # \1 = string of #'s
+        [ \t]%s
+        (.+?)       # \2 = Header text
+        [ \t]*
+        (?<!\\)     # 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):
+        if 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"], 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)
+
+    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(3) in self._marker_ul_chars and "ul" or "ol"
+        result = self._process_list_items(lst)
+        if self.list_level:
+            return "<%s>\n%s</%s>\n" % (lst_type, result, lst_type)
+        else:
+            return "<%s>\n%s</%s>\n\n" % (lst_type, result, lst_type)
+
+    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
+                whole_list = r'''
+                    (                   # \1 = whole list
+                      (                 # \2
+                        [ ]{0,%d}
+                        (%s)            # \3 = first list item marker
+                        [ \t]+
+                        (?!\ *\3\ )     # '- - - ...' isn't a list. See 'not_quite_a_list' test case.
+                      )
+                      (?:.+?)
+                      (                 # \4
+                          \Z
+                        |
+                          \n{2,}
+                          (?=\S)
+                          (?!           # Negative lookahead for another list item marker
+                            [ \t]*
+                            %s[ \t]+
+                          )
+                      )
+                    )
+                ''' % (less_than_tab, marker_pat, 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)
+
+    _last_li_endswith_two_eols = False
+    def _list_item_sub(self, match):
+        item = match.group(4)
+        leading_line = match.group(1)
+        leading_space = match.group(2)
+        if leading_line or "\n\n" in item or self._last_li_endswith_two_eols:
+            item = self._run_block_gamut(self._outdent(item))
+        else:
+            # Recursion for sub-lists:
+            item = self._do_lists(self._outdent(item))
+            if item.endswith('\n'):
+                item = item[:-1]
+            item = self._run_span_gamut(item)
+        self._last_li_endswith_two_eols = (len(match.group(5)) == 2)
+        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 wrap(self, source, outfile):
+                """Return the source with a code, pre, and div."""
+                return self._wrap_div(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, is_fenced_code_block=False):
+        lexer_name = None
+        if is_fenced_code_block:
+            lexer_name = match.group(1)
+            if lexer_name:
+                formatter_opts = self.extras['fenced-code-blocks'] or {}
+            codeblock = match.group(2)
+            codeblock = codeblock[:-1]  # drop one trailing newline
+        else:
+            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
+
+            # Note: "code-color" extra is DEPRECATED.
+            if "code-color" in self.extras and codeblock.startswith(":::"):
+                lexer_name, rest = codeblock.split('\n', 1)
+                lexer_name = lexer_name[3:].strip()
+                codeblock = rest.lstrip("\n")   # Remove lexer declaration line.
+                formatter_opts = self.extras['code-color'] or {}
+
+        if lexer_name:
+            def unhash_code( codeblock ):
+                for key, sanitized in list(self.html_spans.items()):
+                    codeblock = codeblock.replace(key, sanitized)
+                replacements = [
+                    ("&amp;", "&"),
+                    ("&lt;", "<"),
+                    ("&gt;", ">")
+                ]
+                for old, new in replacements:
+                    codeblock = codeblock.replace(old, new)
+                return codeblock
+            lexer = self._get_pygments_lexer(lexer_name)
+            if lexer:
+                codeblock = unhash_code( codeblock )
+                colored = self._color_with_pygments(codeblock, lexer,
+                                                    **formatter_opts)
+                return "\n\n%s\n\n" % colored
+
+        codeblock = self._encode_code(codeblock)
+        pre_class_str = self._html_class_str_from_tag("pre")
+        code_class_str = self._html_class_str_from_tag("code")
+        return "\n\n<pre%s><code%s>%s\n</code></pre>\n\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 tag in html_classes_from_tag:
+                return ' class="%s"' % html_classes_from_tag[tag]
+        return ""
+
+    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.
+            (?![^<]*\</code\>)
+            ''' % (self.tab_width, self.tab_width),
+            re.M | re.X)
+        return code_block_re.sub(self._code_block_sub, text)
+
+    _fenced_code_block_re = re.compile(r'''
+        (?:\n\n|\A\n?)
+        ^```([\w+-]+)?[ \t]*\n      # opening fence, $1 = optional lang
+        (.*?)                       # $2 = code block content
+        ^```[ \t]*\n                # closing fence
+        ''', re.M | re.X | re.S)
+
+    def _fenced_code_block_sub(self, match):
+        return self._code_block_sub(match, is_fenced_code_block=True);
+
+    def _do_fenced_code_blocks(self, text):
+        """Process ```-fenced unindented code blocks ('fenced-code-blocks' extra)."""
+        return self._fenced_code_block_re.sub(self._fenced_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</code>" % c
+
+    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._escape_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)
+    _code_friendly_strong_re = re.compile(r"\*\*(?=\S)(.+?[*_]*)(?<=\S)\*\*", re.S)
+    _code_friendly_em_re = re.compile(r"\*(?=\S)(.+?)(?<=\S)\*", re.S)
+    def _do_italics_and_bold(self, text):
+        # <strong> must go first:
+        if "code-friendly" in self.extras:
+            text = self._code_friendly_strong_re.sub(r"<strong>\1</strong>", text)
+            text = self._code_friendly_em_re.sub(r"<em>\1</em>", text)
+        else:
+            text = self._strong_re.sub(r"<strong>\2</strong>", text)
+            text = self._em_re.sub(r"<em>\2</em>", text)
+        return text
+
+    # "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 _do_smart_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
+
+    # Substitute double-quotes before single-quotes.
+    _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|,|;|\.|\?|!|$))')
+    def _do_smart_punctuation(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._do_smart_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;")
+        return text
+
+    _block_quote_re = re.compile(r'''
+        (                           # Wrap whole match in \1
+          (
+            ^[ \t]*>[ \t]?          # '>' at the start of a line
+              .+\n                  # rest of the first line
+            (.+\n)*                 # subsequent consecutive lines
+            \n*                     # blanks
+          )+
+        )
+        ''', re.M | re.X)
+    _bq_one_level_re = re.compile('^[ \t]*>[ \t]?', 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)
+        bq = self._bq_one_level_re.sub('', bq)  # trim one level of quoting
+        bq = self._ws_only_line_re.sub('', bq)  # trim whitespace-only lines
+        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)
+
+        return "<blockquote>\n%s\n</blockquote>\n\n" % bq
+
+    def _do_block_quotes(self, text):
+        if '>' not in text:
+            return text
+        return self._block_quote_re.sub(self._block_quote_sub, text)
+
+    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]):
+                        start = li.start()
+                        cuddled_list = self._do_lists(graf[start:]).rstrip("\n")
+                        assert cuddled_list.startswith("<ul>") or cuddled_list.startswith("<ol>")
+                        graf = graf[:start]
+
+                # Wrap <p> tags.
+                graf = self._run_span_gamut(graf)
+                grafs.append("<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>',
+            ]
+            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]))
+                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
+
+    # 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+);)')
+    _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 = self._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
+
+    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>' % (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 _do_link_patterns(self, text):
+        """Caveat emptor: there isn't much guarding against link
+        patterns being formed inside other standard Markdown links, e.g.
+        inside a [link def][like this].
+
+        Dev Notes: *Could* consider prefixing regexes with a negative
+        lookbehind assertion to attempt to guard against this.
+        """
+        link_from_hash = {}
+        for regex, repl in self.link_patterns:
+            replacements = []
+            for match in regex.finditer(text):
+                if hasattr(repl, "__call__"):
+                    href = repl(match)
+                else:
+                    href = match.expand(repl)
+                replacements.append((match.span(), href))
+            for (start, end), href in reversed(replacements):
+                escaped_href = (
+                    href.replace('"', '&quot;')  # b/c of attr quote
+                        # To avoid markdown <em> and <strong>:
+                        .replace('*', self._escape_table['*'])
+                        .replace('_', self._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 _unescape_special_chars(self, text):
+        # Swap back in all the special characters we've hidden.
+        for ch, hash in list(self._escape_table.items()):
+            text = text.replace(hash, ch)
+        return text
+
+    def _outdent(self, text):
+        # Remove one level of line-leading tabs or spaces
+        return self._outdent_re.sub('', text)
+
+
+class MarkdownWithExtras(Markdown):
+    """A markdowner class that enables most extras:
+
+    - footnotes
+    - code-color (only has effect 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", "code-color"]
+
+
+#---- internal support functions
+
+class UnicodeWithAttrs(unicode):
+    """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 = None
+    def toc_html(self):
+        """Return the HTML for the current TOC.
+
+        This expects the `_toc` attribute to have been set on this instance.
+        """
+        if self._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 self._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'
+    toc_html = property(toc_html)
+
+## {{{ 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('ascii', '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('/')
+        pattern, 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))
+    indents = []
+    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 = (attr
+        .replace('&', '&amp;')
+        .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)
+
+
+
+#---- mainline
+
+class _NoReflowFormatter(optparse.IndentedHelpFormatter):
+    """An optparse 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()
+
+    usage = "usage: %prog [PATHS...]"
+    version = "%prog "+__version__
+    parser = optparse.OptionParser(prog="markdown2", usage=usage,
+        version=version, description=cmdln_desc,
+        formatter=_NoReflowFormatter())
+    parser.add_option("-v", "--verbose", dest="log_level",
+                      action="store_const", const=logging.DEBUG,
+                      help="more verbose output")
+    parser.add_option("--encoding",
+                      help="specify encoding of text content")
+    parser.add_option("--html4tags", action="store_true", default=False,
+                      help="use HTML 4 style for empty element tags")
+    parser.add_option("-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_option("-x", "--extras", action="append",
+                      help="Turn on specific extra features (not part of "
+                           "the core Markdown spec). See above.")
+    parser.add_option("--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_option("--link-patterns-file",
+                      help="path to a link pattern file")
+    parser.add_option("--self-test", action="store_true",
+                      help="run internal self-tests (some doctests)")
+    parser.add_option("--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, paths = parser.parse_args()
+    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 join, dirname, abspath, exists
+    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 Popen, PIPE
+            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')
+            if py3:
+                sys.stdout.write(perl_html)
+            else:
+                sys.stdout.write(perl_html.encode(
+                    sys.stdout.encoding or "utf-8", 'xmlcharrefreplace'))
+            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)
+        if py3:
+            sys.stdout.write(html)
+        else:
+            sys.stdout.write(html.encode(
+                sys.stdout.encoding or "utf-8", 'xmlcharrefreplace'))
+        if extras and "toc" in extras:
+            log.debug("toc_html: " +
+                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) )
diff --git a/www/models.py b/www/models.py
new file mode 100644
index 0000000..8617d5c
--- /dev/null
+++ b/www/models.py
@@ -0,0 +1,49 @@
+#!/usr/bin/env python3
+# -*- coding: utf-8 -*-
+
+'''
+Models for user, blog, comment.
+'''
+
+__author__ = 'Michael Liao'
+
+import time, uuid
+
+from orm import Model, StringField, BooleanField, FloatField, TextField
+
+def next_id():
+    return '%015d%s000' % (int(time.time() * 1000), uuid.uuid4().hex)
+
+class User(Model):
+    __table__ = 'users'
+
+    id = StringField(primary_key=True, default=next_id, ddl='varchar(50)')
+    email = StringField(ddl='varchar(50)')
+    passwd = StringField(ddl='varchar(50)')
+    admin = BooleanField()
+    name = StringField(ddl='varchar(50)')
+    image = StringField(ddl='varchar(500)')
+    created_at = FloatField(default=time.time)
+
+class Blog(Model):
+    __table__ = 'blogs'
+
+    id = StringField(primary_key=True, default=next_id, ddl='varchar(50)')
+    user_id = StringField(ddl='varchar(50)')
+    user_name = StringField(ddl='varchar(50)')
+    user_image = StringField(ddl='varchar(500)')
+    name = StringField(ddl='varchar(50)')
+    summary = StringField(ddl='varchar(200)')
+    content = TextField()
+    created_at = FloatField(default=time.time)
+
+class Comment(Model):
+    __table__ = 'comments'
+
+    id = StringField(primary_key=True, default=next_id, ddl='varchar(50)')
+    blog_id = StringField(ddl='varchar(50)')
+    user_id = StringField(ddl='varchar(50)')
+    user_name = StringField(ddl='varchar(50)')
+    user_image = StringField(ddl='varchar(500)')
+    content = TextField()
+    created_at = FloatField(default=time.time)
diff --git a/www/orm.py b/www/orm.py
new file mode 100644
index 0000000..ecd7e1d
--- /dev/null
+++ b/www/orm.py
@@ -0,0 +1,229 @@
+#!/usr/bin/env python3
+# -*- coding: utf-8 -*-
+
+__author__ = 'Michael Liao'
+
+import asyncio, logging
+
+import aiomysql
+
+def log(sql, args=()):
+    logging.info('SQL: %s' % sql)
+
+async def create_pool(loop, **kw):
+    logging.info('create database connection pool...')
+    global __pool
+    __pool = yield from aiomysql.create_pool(
+        host=kw.get('host', 'localhost'),
+        port=kw.get('port', 3306),
+        user=kw['user'],
+        password=kw['password'],
+        db=kw['db'],
+        charset=kw.get('charset', 'utf8'),
+        autocommit=kw.get('autocommit', True),
+        maxsize=kw.get('maxsize', 10),
+        minsize=kw.get('minsize', 1),
+        loop=loop
+    )
+
+async def select(sql, args, size=None):
+    log(sql, args)
+    global __pool
+    async with __pool.get() as conn:
+        async with conn.cursor(aiomysql.DictCursor) as cur:
+            await cur.execute(sql.replace('?', '%s'), args or ())
+            if size:
+                rs = await cur.fetchmany(size)
+            else:
+                rs = await cur.fetchall()
+        logging.info('rows returned: %s' % len(rs))
+        return rs
+
+async def execute(sql, args, autocommit=True):
+    log(sql)
+    async with __pool.get() as conn:
+        if not autocommit:
+            await conn.begin()
+        try:
+            async with conn.cursor(aiomysql.DictCursor) as cur:
+                await cur.execute(sql.replace('?', '%s'), args)
+                affected = cur.rowcount
+            if not autocommit:
+                await conn.commit()
+        except BaseException as e:
+            if not autocommit:
+                await conn.rollback()
+            raise
+        return affected
+
+def create_args_string(num):
+    L = []
+    for n in range(num):
+        L.append('?')
+    return ', '.join(L)
+
+class Field(object):
+
+    def __init__(self, name, column_type, primary_key, default):
+        self.name = name
+        self.column_type = column_type
+        self.primary_key = primary_key
+        self.default = default
+
+    def __str__(self):
+        return '<%s, %s:%s>' % (self.__class__.__name__, self.column_type, self.name)
+
+class StringField(Field):
+
+    def __init__(self, name=None, primary_key=False, default=None, ddl='varchar(100)'):
+        super().__init__(name, ddl, primary_key, default)
+
+class BooleanField(Field):
+
+    def __init__(self, name=None, default=False):
+        super().__init__(name, 'boolean', False, default)
+
+class IntegerField(Field):
+
+    def __init__(self, name=None, primary_key=False, default=0):
+        super().__init__(name, 'bigint', primary_key, default)
+
+class FloatField(Field):
+
+    def __init__(self, name=None, primary_key=False, default=0.0):
+        super().__init__(name, 'real', primary_key, default)
+
+class TextField(Field):
+
+    def __init__(self, name=None, default=None):
+        super().__init__(name, 'text', False, default)
+
+class ModelMetaclass(type):
+
+    def __new__(cls, name, bases, attrs):
+        if name=='Model':
+            return type.__new__(cls, name, bases, attrs)
+        tableName = attrs.get('__table__', None) or name
+        logging.info('found model: %s (table: %s)' % (name, tableName))
+        mappings = dict()
+        fields = []
+        primaryKey = None
+        for k, v in attrs.items():
+            if isinstance(v, Field):
+                logging.info('  found mapping: %s ==> %s' % (k, v))
+                mappings[k] = v
+                if v.primary_key:
+                    # 找到主键:
+                    if primaryKey:
+                        raise StandardError('Duplicate primary key for field: %s' % k)
+                    primaryKey = k
+                else:
+                    fields.append(k)
+        if not primaryKey:
+            raise StandardError('Primary key not found.')
+        for k in mappings.keys():
+            attrs.pop(k)
+        escaped_fields = list(map(lambda f: '`%s`' % f, fields))
+        attrs['__mappings__'] = mappings # 保存属性和列的映射关系
+        attrs['__table__'] = tableName
+        attrs['__primary_key__'] = primaryKey # 主键属性名
+        attrs['__fields__'] = fields # 除主键外的属性名
+        attrs['__select__'] = 'select `%s`, %s from `%s`' % (primaryKey, ', '.join(escaped_fields), tableName)
+        attrs['__insert__'] = 'insert into `%s` (%s, `%s`) values (%s)' % (tableName, ', '.join(escaped_fields), primaryKey, create_args_string(len(escaped_fields) + 1))
+        attrs['__update__'] = 'update `%s` set %s where `%s`=?' % (tableName, ', '.join(map(lambda f: '`%s`=?' % (mappings.get(f).name or f), fields)), primaryKey)
+        attrs['__delete__'] = 'delete from `%s` where `%s`=?' % (tableName, primaryKey)
+        return type.__new__(cls, name, bases, attrs)
+
+class Model(dict, metaclass=ModelMetaclass):
+
+    def __init__(self, **kw):
+        super(Model, self).__init__(**kw)
+
+    def __getattr__(self, key):
+        try:
+            return self[key]
+        except KeyError:
+            raise AttributeError(r"'Model' object has no attribute '%s'" % key)
+
+    def __setattr__(self, key, value):
+        self[key] = value
+
+    def getValue(self, key):
+        return getattr(self, key, None)
+
+    def getValueOrDefault(self, key):
+        value = getattr(self, key, None)
+        if value is None:
+            field = self.__mappings__[key]
+            if field.default is not None:
+                value = field.default() if callable(field.default) else field.default
+                logging.debug('using default value for %s: %s' % (key, str(value)))
+                setattr(self, key, value)
+        return value
+
+    @classmethod
+    async def findAll(cls, where=None, args=None, **kw):
+        ' find objects by where clause. '
+        sql = [cls.__select__]
+        if where:
+            sql.append('where')
+            sql.append(where)
+        if args is None:
+            args = []
+        orderBy = kw.get('orderBy', None)
+        if orderBy:
+            sql.append('order by')
+            sql.append(orderBy)
+        limit = kw.get('limit', None)
+        if limit is not None:
+            sql.append('limit')
+            if isinstance(limit, int):
+                sql.append('?')
+                args.append(limit)
+            elif isinstance(limit, tuple) and len(limit) == 2:
+                sql.append('?, ?')
+                args.extend(limit)
+            else:
+                raise ValueError('Invalid limit value: %s' % str(limit))
+        rs = yield from select(' '.join(sql), args)
+        return [cls(**r) for r in rs]
+
+    @classmethod
+    async def findNumber(cls, selectField, where=None, args=None):
+        ' find number by select and where. '
+        sql = ['select %s _num_ from `%s`' % (selectField, cls.__table__)]
+        if where:
+            sql.append('where')
+            sql.append(where)
+        rs = yield from select(' '.join(sql), args, 1)
+        if len(rs) == 0:
+            return None
+        return rs[0]['_num_']
+
+    @classmethod
+    async def find(cls, pk):
+        ' find object by primary key. '
+        rs = yield from select('%s where `%s`=?' % (cls.__select__, cls.__primary_key__), [pk], 1)
+        if len(rs) == 0:
+            return None
+        return cls(**rs[0])
+
+    async def save(self):
+        args = list(map(self.getValueOrDefault, self.__fields__))
+        args.append(self.getValueOrDefault(self.__primary_key__))
+        rows = yield from execute(self.__insert__, args)
+        if rows != 1:
+            logging.warn('failed to insert record: affected rows: %s' % rows)
+
+    async def update(self):
+        args = list(map(self.getValue, self.__fields__))
+        args.append(self.getValue(self.__primary_key__))
+        rows = yield from execute(self.__update__, args)
+        if rows != 1:
+            logging.warn('failed to update by primary key: affected rows: %s' % rows)
+
+    async def remove(self):
+        args = [self.getValue(self.__primary_key__)]
+        rows = yield from execute(self.__delete__, args)
+        if rows != 1:
+            logging.warn('failed to remove by primary key: affected rows: %s' % rows)
diff --git a/www/static/README b/www/static/README
new file mode 100644
index 0000000..8f73286
--- /dev/null
+++ b/www/static/README
@@ -0,0 +1 @@
+stores static files.