static LL<S> ai_all_threeInARow(S base) {
  Map<BigInt, S> map = ai_search_allNumbered_asMap(base);
  L<BigInt> l = keysList(map);
  new LL<S> out;
  for (int i = 0; i+2 < l(l); i++) {
    BigInt a = l.get(i), b = l.get(i+1), c = l.get(i+2);
    if (eq(plus(a, 1), b) && eq(plus(a, 2), c))
      out.add(ll(map.get(a), map.get(b), map.get(c)));
  }
  ret out;
}