static <A> LL<A> splitAroundSubListIndices(L<A> x, L<Int> indices, int subListLength) {
  new LL<A> l;
  for (int i = 0; i <= l(indices); i++)
    l.add(subList(x, 
      i == 0 ? 0 : indices.get(i-1)+subListLength,
      i == l(indices) ? l(x) : indices.get(i)));
  ret l;
}