code: def pypi_render(source):
      
      ALLOWED_SCHEMES = '''file ftp gopher hdl http https imap mailto mms news
          nntp prospero rsync rtsp rtspu sftp shttp sip sips snews svn svn+ssh
          telnet wais irc'''.split()
  
      settings_overrides = {
          "raw_enabled": 0,  # no raw HTML code
          "file_insertion_enabled": 0,  # no file/URL access
          "halt_level": 2,  # at warnings or errors, raise an exception
          "report_level": 5,  # never report problems with the reST code
      }
  
      # capture publishing errors, they go to stderr
      old_stderr = sys.stderr
      sys.stderr = s = StringIO.StringIO()
      parts = None
  
      try:
          # Convert reStructuredText to HTML using Docutils.
          document = publish_doctree(source=source,
              settings_overrides=settings_overrides)
  
          for node in document.traverse():
              if node.tagname == '#text':
                  continue
              if node.hasattr('refuri'):
                  uri = node['refuri']
              elif node.hasattr('uri'):
                  uri = node['uri']
              else:
                  continue
              o = urlparse.urlparse(uri)
              if o.scheme not in ALLOWED_SCHEMES:
                  raise TransformError('link scheme not allowed')
  
          # now turn the transformed document into HTML
          reader = readers.doctree.Reader(parser_name='null')
          pub = Publisher(reader, source=io.DocTreeInput(document),
              destination_class=io.StringOutput)
          pub.set_writer('html')
          pub.process_programmatic_settings(None, settings_overrides, None)
          pub.set_destination(None, None)
          pub.publish()
          parts = pub.writer.parts
  
      except:
          pass
  
      sys.stderr = old_stderr
  
      # original text if publishing errors occur
      if parts is None or len(s.getvalue()) > 0:
          return None
      else:
          return parts['body']
docs: Copied (and slightly adapted) from pypi.description_tools