static LL<S> tok_marchPatternThroughInput(LS patTok, LS inputTok) {
  int lp = l(patTok);
  int n = l(inputTok)-lp+1;
  new LL<S> out;
  for (int i = 0; i < n; i += 2)
    out.add(subList(inputTok, i, i+lp));
  ret out;
}