static void ai_spec_tripelize(S s) {
  new Matches m;
  T3<S> t = ai_tripelize(s);
  if (!ai_trivialTriple(t))
    ai_postTriple(s, "possibly parses to triple", curlyBraceIfMoreThanOneToken(t.a) + " -> " + curlyBraceIfMoreThanOneToken(t.b) + " -> " +  curlyBraceIfMoreThanOneToken(t.c));
}