code: func (db *DB) Del(keys ...[]byte) (int64, error) {
  	if len(keys) == 0 {
  		return 0, nil
  	}
  
  	codedKeys := make([][]byte, len(keys))
  	for i, k := range keys {
  		codedKeys[i] = db.encodeKVKey(k)
  	}
  
  	t := db.kvBatch
  	t.Lock()
  	defer t.Unlock()
  
  	for i, k := range keys {
  		t.Delete(codedKeys[i])
  		db.rmExpire(t, KVType, k)
  	}
  
  	err := t.Commit()
  	return int64(len(keys)), err
  }
docs: // Del deletes the data.