static L<Int> ai_findSpreadOutWords(LS tok, S... words) {
  int i = 1, iWord = 0, nWords = l(words), nTok = l(tok);
  new L<Int> indices;
  while (iWord < nWords) {
    if (i >= nTok) null; // fail
    if (eqic(tok.get(i), words[iWord])) {
      indices.add(i);
      ++iWord;
    }
    i += 2;
  }
  ret indices;
}