code: def payload_class_for_element_name(element_name):
      
      logger.debug(" looking up payload class for element: {0!r}".format(
                                                                  element_name))
      logger.debug("  known: {0!r}".format(STANZA_PAYLOAD_CLASSES))
      if element_name in STANZA_PAYLOAD_CLASSES:
          return STANZA_PAYLOAD_CLASSES[element_name]
      else:
          return XMLPayload
docs: Return a payload class for given element name.