static <A> L<A> listMinusSet(Iterable<A> l, Collection<? extends A> stuff) {
  if (l == null) null;
  if (empty(stuff)) ret asList(l);
  Set<? extends A> set = asSet(stuff);
  new L<A> l2;
  for (A a : l) if (!set.contains(a)) l2.add(a);
  ret l2;
}

static <A> L<A> listMinusSet(Iterable<A> l, Collection<A> stuff, Collection<? extends A> stuff2) {
  ret listMinusSet(listMinusSet(l, stuff), stuff2);
}