backends

type ReadSeekCloser interface {
	io.Reader
	io.Closer
	io.Seeker
	io.ReaderAt
}

type StorageBackend interface {
	Delete(key string) error
	Exists(key string) (bool, error)
	Get(key string) ([]byte, error)
	Put(key string, r io.Reader) (int64, error)
	Open(key string) (ReadSeekCloser, error)
	ServeFile(key string, w http.ResponseWriter, r *http.Request)
	Size(key string) (int64, error)
}