// index, exact will be false and the compact index will be returned for the
// first match after repeatedly taking the Parent of t.
func CompactIndex(t Tag) (index int, exact bool) {
	id, exact := compact.LanguageID(compact.Tag(t))
	return int(id), exact
}

var root = language.Tag{}

// Base is an ISO 639 language code, used for encoding the base language
// of a language tag.
type Base struct {