simple

type Entry interface {
	// Reference returns the address of the file in the entry.
	Reference() string
	// Metadata returns the metadata for this entry.
	Metadata() map[string]string
}

type Manifest interface {
	// Add adds a manifest entry to the specified path.
	Add(string, string, map[string]string) error
	// Remove removes a manifest entry on the specified path.
	Remove(string) error
	// Lookup returns a manifest node entry if one is found in the specified path.
	Lookup(string) (Entry, error)
	// HasPrefix tests whether the specified prefix path exists.
	HasPrefix(string) bool
	// Length returns an implementation-specific count of elements in the manifest.
	// For Manifest, this means the number of all the existing entries.
	Length() int

	// WalkEntry walks all entries, calling walkFn for each entry in the map.
	// All errors that arise visiting entires are filtered by walkFn.
	WalkEntry(string, WalkEntryFunc) error

	encoding.BinaryMarshaler
	encoding.BinaryUnmarshaler
}

type WalkEntryFunc func(path string, entry Entry, err error) error