code: func (db *DB) ZClear(key []byte) (int64, error) {
  	t := db.zsetBatch
  	t.Lock()
  	defer t.Unlock()
  
  	rmCnt, err := db.zRemRange(t, key, MinScore, MaxScore, 0, -1)
  	if err == nil {
  		err = t.Commit()
  	}
  
  	return rmCnt, err
  }
docs: // ZClear clears the zset.