static ItIt mapLike multiCall(O f, O... args) {
  new L<Iterable<O>> lists;
  for (O arg : args)
    if (arg cast Multi)
      lists.add(arg.arguments);
    else
      lists.add(ll(arg));
  ret mapI(outerProduct_arrays(lists), args2 -> callF(f, args2));
}