static S renderMultiSet(MultiSet ms) {
  if (ms == null) ret "-";
  new L<S> l;
  for (O o : ms.highestFirst())
    l.add(str(o) + " (" + ms.get(o) + ")");
  ret joinWithComma(l);
}

static <A> S renderMultiSet(Iterable<A> l) {
  ret renderMultiSet(toMultiSet(l));
}