static L<S> ai_texts_multi(L<S> a, L<S> b, L<S> c) {
  new LinkedHashSet<S> l;
  if (empty(a) || empty(b) || empty(c)) ret l;
  for (S _a : a)
    for (S _b : b)
      for (S _c : c)
        l.addAll(ai_texts(_a, _b, _c));
  ret cloneList(l);
}

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

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

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