static LS splitByZeroIndent(S s) {
  LS lines = lines(s);
  new LS out;
  int j = 0;
  for i over lines: {
    if (!startsWithSpace(lines.get(i))) {
      if (i > j)
        out.add(lines(subList(lines, j, i)));
      j = i;
    }
  }
  if (j < l(lines))
    out.add(lines(subList(lines, j)));
  ret out;
}