code: def route_stanza(self, stanza):
          
          if stanza.stanza_type not in ("error", "result"):
              response = stanza.make_error_response(u"recipient-unavailable")
              self.send(response)
          return True
docs: Process stanza not addressed to us.
  
          Return "recipient-unavailable" return if it is not
          "error" nor "result" stanza.
  
          This method should be overriden in derived classes if they
          are supposed to handle stanzas not addressed directly to local
          stream endpoint.
  
          :Parameters:
              - `stanza`: presence stanza to be processed