static <A> L<A> takeUntil(Iterable<A> l, bool includeLast, IF1<A, Bool> pred) {
  new L<A> out;
  fOr (A a : l)
    if (pred.get(a)) {
      if (includeLast)
        out.add(a);
      ret out;
    } else
      out.add(a);
  ret out;
}