svoid printAllConceptChanges(Concepts cc default db_mainConcepts()) {
  cc.addConceptIndex(new IConceptIndex {
    public void update(Concept c) { print("Updated: " + c); }
    public void remove(Concept c) { print("Removed: " + c); }
  });
  cc.onAllChanged.add(r { print("General concepts change"); });
}