code: func (q *Queue) delete(key []byte) {
  	err := q.db.Delete([]byte(key), nil)
  	atomic.AddUint32(&q.stat.deleteCount, 1)
  	if err != nil {
  		atomic.AddUint32(&q.stat.deleteErrors, 1)
  		q.logger.Error("delete from queue database failed", zap.Error(err))
  	}
  }
docs: // Remove key from queue