static <A> LL<A> mapLike streaksAndNonStreaks(O pred, L<A> l) {
  new LL<A> out;
  int start = 0;
  Bool last = null;
  for i over l: {
    Bool result = (Bool) callF(pred, l.get(i));
    if (last != null && result != null && neq(result, last)) {
      out.add(subList(l, start, i));
      start = i;
    }
    if (result != null) last = result;
  }
  if (start < l(l))
    out.add(subList(l, start));
  ret out;
}