sbool indexSingletonConceptIfUnindexed(Concepts cc, Class<? extends Concept> c) {
  if (isConceptClassIndexed(cc, c)) false;
  indexSingletonConcept(cc, c);
  true;
}

sbool nuLike indexSingletonConceptIfUnindexed(Class<? extends Concept> c) {
  ret indexSingletonConceptIfUnindexed(db_mainConcepts(), c);
}