static <A extends Concept> void importAllConceptsOfType(Class<A> cClass, Cl<A> l) {
  Concepts cc = db_mainConcepts();
  Set<Long> ids = mapToSet(l, c -> c.id);
  fOr (A c : l) {
    A existing = cast cc.getConcept(c.id);
    if (existing == null)
      cc.register(existing = c);
    else
      copyConceptFields(c, existing);
  }
  for (A c : cloneList(list(cc, cClass)))
    if (!ids.contains(c.id))
      deleteConcept(c);
}