static <A extends Concept> Pair<A, Bool> nuLike uniq2(Class<A> c, O... params) {
  ret uniq2(db_mainConcepts(), c, params);
}

static <A extends Concept> Pair<A, Bool> uniq2(Concepts cc, Class<A> c, O... params) {
  temp tempDBLock(cc);
  params = expandParams(c, params);
  A x = findConceptWhere(cc, c, params);
  if (x == null) {
    x = unlisted(c);
    csetAll(x, params);
    cc.register(x);
    ret pair(x, true);
  }
  ret pair(x, false);
}