Tell pika to call the on_channel_closed method if
        RabbitMQ unexpectedly closes the channel.

def add_on_channel_close_callback(self):
        """
        Tell pika to call the on_channel_closed method if
        RabbitMQ unexpectedly closes the channel.
        """
        self._logger.info('Adding channel close callback')
        self._channel.add_on_close_callback(self.on_channel_closed)