code: def MarkdownColumn(name, deferred=False, group=None, **kwargs):
      
      return composite(MarkdownComposite,
          Column(name + '_text', UnicodeText, **kwargs),
          Column(name + '_html', UnicodeText, **kwargs),
          deferred=deferred, group=group or name
      )
docs: Create a composite column that autogenerates HTML from Markdown text,
      storing data in db columns named with ``_html`` and ``_text`` prefixes.