type Backend interface {
	BatchTx() BatchTx
	Snapshot(w io.Writer) (n int64, err error)
	ForceCommit()
	Close() error
}

type BatchTx interface {
	Lock()
	Unlock()
	UnsafeCreateBucket(name []byte)
	UnsafePut(bucketName []byte, key []byte, value []byte)
	UnsafeRange(bucketName []byte, key, endKey []byte, limit int64) (keys [][]byte, vals [][]byte)
	UnsafeDelete(bucketName []byte, key []byte)
	Commit()
}