content: import markdown
  from markdown.inlinepatterns import SimpleTagPattern
  
  __all__ = (
      'StrikethroughExtension',
  )
  
  STRIKE_RE = r'(~{2})(.+?)(~{2})'
  
  
  class StrikethroughExtension(markdown.Extension):
      """
      A python-markdown extension which support strikethrough formatting (e.g. "~~text~~").
      """
      def extendMarkdown(self, md):
          md.inlinePatterns.register(
              SimpleTagPattern(STRIKE_RE, 'del'),
              'strikethrough',
              200
          )
  