code: def __on_connect(self, client, userdata, flags, result_code):
          # pylint: disable=W0613
          
          if result_code:
              # result_code != 0: something wrong happened
              _logger.error(
                  "Error connecting the MQTT server: %s (%d)",
                  paho.connack_string(result_code),
                  result_code,
              )
          else:
              # Connection is OK: stop the reconnection timer
              self.__stop_timer()
  
          # Notify the caller, if any
          if self.on_connect is not None:
              try:
                  self.on_connect(self, result_code)
              except Exception as ex:
                  _logger.exception("Error notifying MQTT listener: %s", ex)
docs: Client connected to the server
  
          :param client: Connected Paho client
          :param userdata: User data (unused)
          :param flags: Response flags sent by the broker
          :param result_code: Connection result code (0: success, others: error)