static bool has_multi(L<S> a, L<S> b, L<S> c) {
  for (S _a : a)
    for (S _b : b)
      for (S _c : c)
        if (has(_a, _b, _c)) true;
  false;
}

static bool has_multi(S a, L<S> b, S c) {
  ret has_multi(ll(a), b, ll(c));
}

static bool has_multi(L<S> a, L<S> b, S c) {
  ret has_multi(a, b, ll(c));
}

static bool has_multi(L<S> a, S b, L<S> c) {
  ret has_multi(a, ll(b), c);
}

Began life as a copy of #1012596