sbool aiUsing_enabled;
static Set<S> aiUsing_set = synchroTreeSet();

static S aiUsing(S s) {
  if (aiUsing_enabled)
    aiUsing_set.addAll(aggressivelyCollectPossibleGlobalIDs(s));
  ret s;
}

static void aiUsing(O o) {
  // TODO
}

static <A> L<A> aiUsing(L<A> l) {
  if (aiUsing_enabled)
    for (O li : unnull(l)) aiUsing(li);
  ret l;
}

static Lisp aiUsing(Lisp l) {
  if (aiUsing_enabled && l != null) {
    aiUsing(l.head);
    for (Lisp sub : l) aiUsing(sub);
  }
  ret l;
}