static <A extends Concept> Cl<A> cForwardAndBackRefs(Concept c, Class<A> type) {
  ret concatLists_conservative(cForwardRefs(c, type), findBackRefs(c, type));
}

static <A extends Concept> Cl<A> nuLike cForwardAndBackRefs(Class<A> type, Concept c) {
  ret cForwardAndBackRefs(c, type);
}