static L<S> splitAfterChars_trim(S chars, S s) {
  new L<S> out;
  L<int> l = indexesOfCharacters(s, chars);
  addFirstUnlessThere(l, 0);
  addUnlessThere(l, l(s));
  for (int i = 0; i+1 < l(l); i++) {
    S x = trim(substring(s, l.get(i), l.get(i+1)));
    if (nempty(x)) out.add(x);
  }
  ret out;
}