// doesn't trigger on remove, just register and update
static <A extends Concept> void nuLike onIndividualConceptChange_notOnAllChanged(Concepts cc default db_mainConcepts(), Class<A> type, IVF1<A> r) {
  if (r != null) cc?.addConceptIndex(new IConceptIndex {
    public void update(Concept c) {
      if (instanceOf(c, type))
        r.get((A) c);
    }
    public void remove(Concept c) {}
  });
}

Began life as a copy of #1028823