code: def _process_incoming_message(self, stanza_obj):
          
          self._logger.debug("incoming message: %r", stanza_obj)
  
          stanza_obj = self.service_inbound_message_filter.filter(stanza_obj)
          if stanza_obj is None:
              self._logger.debug("incoming message dropped by service "
                                 "filter chain")
              return
  
          stanza_obj = self.app_inbound_message_filter.filter(stanza_obj)
          if stanza_obj is None:
              self._logger.debug("incoming message dropped by application "
                                 "filter chain")
              return
  
          self.on_message_received(stanza_obj)
docs: Process an incoming message stanza `stanza_obj`.