def on_connection_open(self, unused_connection):
        """
        Called by pika once the connection to RabbitMQ has
        been established. It passes the handle to the connection object in
        case we need it, but in this case, we'll just mark it unused.

        :type unused_connection: pika.SelectConnection
        """
        self._logger.info('Connection opened')
        self.add_on_connection_close_callback()
        self.open_channel()
Called by pika once the connection to RabbitMQ has
        been established. It passes the handle to the connection object in
        case we need it, but in this case, we'll just mark it unused.

        :type unused_connection: pika.SelectConnection