static HashMap listToKeysWithCalculatedValue(Iterable l, O f) {
  ret listToKeysWithCalculatedValue(f, l);
}

static HashMap listToKeysWithCalculatedValue(O f, Iterable l) {
  new HashMap map;
  if (l != null) for (O o : l)
    map.put(o, callF(f, o));
  ret map;
}