static L<S> ai_isAWhat(S s) {
  new LinkedHashSet<S> l;
  S s1 = quote(s), s2 = unquote(s);
  l.addAll(ai_texts(s1, "is a", "$X"));
  l.addAll(ai_texts(s2, "is a", "$X"));
  ret cloneList(l);
}