code: func (consumer *Consumer) GetFailed() (*Package, error) {
  	answer := consumer.Queue.redisClient.RPopLPush(
  		queueFailedKey(consumer.Queue.Name),
  		consumerWorkingQueueKey(consumer.Queue.Name, consumer.Name),
  	)
  	consumer.Queue.incrRate(
  		consumerWorkingRateKey(consumer.Queue.Name, consumer.Name),
  		1,
  	)
  	return consumer.parseRedisAnswer(answer)
  }
docs: // GetFailed returns a single packages from the failed queue of this consumer