docs: def delivery_report(err, msg):
          """
          Callback called once for each produced message to indicate the final
          delivery result. Triggered by poll() or flush().
  
          :param confluent_kafka.KafkaError err: Information about any error
          that occurred whilst producing the message.
          :param confluent_kafka.Message msg: Information about the message
          produced.
          :returns: None
          :raises confluent_kafka.KafkaException
          """
  
          if err is not None:
              log.exception(u'Message delivery failed: {}'.format(err))
              raise confluent_kafka.KafkaException(err)
          else:
              log.debug(u'Message delivered to {} [{}]: {}'.format(
                  msg.topic(), msg.partition(), msg.value()))