code: func (mvcc *MVCCLevelDB) Rollback(keys [][]byte, startTS uint64) error {
  	mvcc.mu.Lock()
  	defer mvcc.mu.Unlock()
  
  	batch := &leveldb.Batch{}
  	for _, k := range keys {
  		err := rollbackKey(mvcc.db, batch, k, startTS)
  		if err != nil {
  			return errors.Trace(err)
  		}
  	}
  	return mvcc.db.Write(batch, nil)
  }
docs: // Rollback implements the MVCCStore interface.