static <A, B> Map<A, B> mapMinusKeys(Map<A, B> map, A... keys) {
  ret mapMinusKeys(map, asList(keys));
}

static <A, B> Map<A, B> mapMinusKeys(Map<A, B> map, Cl<A> keys) {
  if (empty(keys) || empty(map)) ret map;
  keys = asSet(keys);
  Map<A, B> m2 = similarEmptyMap(map);
  for (A key, B val : map)
    if (!keys.contains(key))
      m2.put(key, val);
  ret m2;
}

static <A, B> Map<A, B> mapMinusKeys(Cl<A> keys, Map<A, B> map) {
  ret mapMinusKeys(map, keys);
}