// TODO: this doesn't really make sense right now as
// onAllChanged is called on every change. We need a new
// event type "unknown change" or something.
svoid nuLike onConceptChangeByClass(Class type, Runnable r) {
  onConceptChangeByClass(db_mainConcepts(), type, r);
}

svoid onConceptChangeByClass(Concepts cc, Class type, Runnable r) {
  onConceptChangeByClass_notOnAllChanged(cc, type, r);
  cc.onAllChanged.add(r);
}

Began life as a copy of #1016028