static Set<S> ai_mostLikelyVariables(S s) {
  Set<S> set = asSet(javaTok_cached(s));
  if (contains(set, "X")) ret intersectSetWithItems(set, "X", "Y", "Z");
  if (any isDollarVar(set)) ret filterSet isDollarVar(set);
  if (contains(set, "*")) ret litset("*");
  null;
}