static <A extends Concept> A latest(Class<A> c) {
  long maxID = 0;
  A max = null;
  
  for (A a : list(c))
    if (a.id > maxID) {
      maxID = a.id;
      max = a;
    }
  ret max;

  // This doesn't work:
  //ret last(list(c)); // todo: optimize?
}