code: def serialize(self, value):
      
      if six.PY2:
        # In Python2 csv.writer doesn't accept unicode, so we convert to UTF-8.
        output = io.BytesIO()
        csv.writer(output).writerow([unicode(x).encode('utf-8') for x in value])
        serialized_value = output.getvalue().decode('utf-8').strip()
      else:
        # In Python3 csv.writer expects a text stream.
        output = io.StringIO()
        csv.writer(output).writerow([str(x) for x in value])
        serialized_value = output.getvalue().strip()
  
      # We need the returned value to be pure ascii or Unicodes so that
      # when the xml help is generated they are usefully encodable.
      return _helpers.StrOrUnicode(serialized_value)
docs: Serialize a list as a string, if possible, or as a unicode string.