backend

type Backend interface {
	GetFile(*FileKey) (io.Reader, bool, error)
	PutFile(*FileKey, io.Reader) error
	GetSnap(*SnapKey) (io.Reader, bool, error)
	PutSnap(*SnapKey, io.Reader) (bool, error)
}

type FileKey struct {
	Base     string
	Snapshot string
	FilePath string
}

type SnapKey struct {
	Base     string
	Snapshot string
}