static <A, B, C> Map<A, C> mapKeyAndFunction(Map<A, B> map, IF2<A, B, C> f) {
  new HashMap map2;
  if (map != null) for (A key, B value : map)
    map2.put(key, callF(f, key, value));
  ret map2;
}


static <A, B, C extends Cl<A>> MultiMap<A, B> mapToMultiMapValues(Iterable<A> l, IF1<A, C> f) {
  new MultiMap<A, B> mm;
  fOr (a : l)
    mm.put(a, f.get(a));
  ret mm;
}