static <A, B> void changeKeyAndModifyValue(Map<A, B> map, A oldKey, A newKey, IF1<B> f) {
  if (map == null || eq(oldKey, newKey) || !map.containsKey(oldKey)) ret;
  B value = map.get(oldKey);
  map.put(newKey, f.get(value));
  map.remove(oldKey);
}