svoid indexSingletonConceptIfUnindexed(Concepts cc, Class<? extends Concept> c) {
  if (!isConceptClassIndexed(cc, c))
    indexSingletonConcept(cc, c);
}

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