code: func (mvcc *MVCCLevelDB) doRawDeleteRange(startKey, endKey []byte) error {
  	mvcc.mu.Lock()
  	defer mvcc.mu.Unlock()
  
  	batch := &leveldb.Batch{}
  
  	iter := mvcc.db.NewIterator(&util.Range{
  		Start: startKey,
  		Limit: endKey,
  	}, nil)
  	for iter.Next() {
  		batch.Delete(iter.Key())
  	}
  
  	return mvcc.db.Write(batch, nil)
  }
docs: // doRawDeleteRange deletes all keys in a range and return the error if any.