Check in a simple pure-python based Markdown previewer.

third_party/Python-Markdown/markdown/extensions/nl2br.py

+"""
+NL2BR Extension
+===============
+
+A Python-Markdown extension to treat newlines as hard breaks; like
+GitHub-flavored Markdown does.
+
+See <https://pythonhosted.org/Markdown/extensions/nl2br.html>
+for documentation.
+
+Oringinal code Copyright 2011 [Brian Neal](http://deathofagremmie.com/)
+
+All changes Copyright 2011-2014 The Python Markdown Project
+
+License: [BSD](http://www.opensource.org/licenses/bsd-license.php)
+
+"""
+
+from __future__ import absolute_import
+from __future__ import unicode_literals
+from . import Extension
+from ..inlinepatterns import SubstituteTagPattern
+
+BR_RE = r'\n'
+
+
+class Nl2BrExtension(Extension):
+
+    def extendMarkdown(self, md, md_globals):
+        br_tag = SubstituteTagPattern(BR_RE, 'br')
+        md.inlinePatterns.add('nl', br_tag, '_end')
+
+
+def makeExtension(*args, **kwargs):
+    return Nl2BrExtension(*args, **kwargs)