// returns actual CNC
static ItIt<LS> subtokenizationsOfAnyLength(LS tok) {
  int n = countTokens(tok);
  ItIt<Int> itLength = countIterator_inclusive(1, n);
  ret nestedIterator(itLength, length -> // how many tokens to get
    mapI(countIterator_inclusive(0, n-length), i -> // first token to get
      i -> subList(tok, i*2, (i+length)*2+1)));
}