static Map mapKeysAndValues(O f, Map map) {
  ret mapKeysAndValues(f, f, map);
}

static Map mapKeysAndValues(O fKey, O fValue, Map map) {
  Map m = similarEmptyMap(map);
  for (O key : keys(map))
    m.put(callF(fKey, key), callF(fValue, map.get(key)));
  ret m;
}