code: def handle_authorized(self, event):
          
          stream = event.stream
          if not stream:
              return
          if not stream.initiator:
              return
          if stream.features is None:
              return
          element = stream.features.find(SESSION_TAG)
          if element is None:
              return
          logger.debug("Establishing IM session")
          stanza = Iq(stanza_type = "set")
          payload = XMLPayload(ElementTree.Element(SESSION_TAG))
          stanza.set_payload(payload)
          self.stanza_processor.set_response_handlers(stanza,
                                          self._session_success,
                                          self._session_error)
          stream.send(stanza)
docs: Send session esteblishment request if the feature was advertised by
          the server.