static <K, T> Keyed<K,T>
of(K key, T val)
static <K, T> Function<T,Keyed<K,T>>
keyed(Function<? super T,K> keyMapper)
static <T, K, V> Function<Map.Entry<Keyed<K,T>,V>,T>
kkv()
static <K, T> Function<Keyed<K,T>,T>
val()