static T3<S> ai_webToTriple(Web web) {
  if (web == null) null;
  L<WebRelation> l = web_relationObjects(web);
  if (l(l) != 1) null;
  WebRelation r = first(l);
  ret t3(web_text_assertOne(r.a), web_text_assertOne(r), web_text_assertOne(r.b));
}