static <A extends Concept> int countConcepts(Class<A> c, O... params) {
  int n = 0;
  if (l(params) == 0) ret l(list(c));
  for (A x : list(c))
    if (checkConceptFields(x, params))
      ++n;
  ret n;
}

static int countConcepts() {
  ret l(concepts);
}