svoid nuLike onConceptChangeByClass(Class type, Runnable r) {
  onConceptChangeByClass(db_mainConcepts(), type, r);
}

svoid onConceptChangeByClass_notOnAllChanged(Concepts cc, Class type, Runnable r) {
  cc.addConceptIndex(new IConceptIndex {
    public void update(Concept c) { if (instanceOf(c, type)) pcallF(r); }
    public void remove(Concept c) { if (instanceOf(c, type)) pcallF(r); }
  });
  c.onAllChanged(r);
}