docs: def on_disconnect(self, client, userdata, result_code):
          """ Callback when the MQTT client is disconnected. In this case,
              the server waits five seconds before trying to reconnected.
  
          :param client: the client being disconnected.
          :param userdata: unused.
          :param result_code: result code.
          """
          self.log_info("Disconnected with result code " + str(result_code))
          self.state_handler.set_state(State.goodbye)
          time.sleep(5)
          self.thread_handler.run(target=self.start_blocking)