docs: public static <T1 extends Comparable<T1>, T2 extends Comparable<T2>> Comparator<Pair<T1, T2>> naturalOrder() {
          return new Comparator<Pair<T1,T2>>() {
  
              @Override
              public int compare(Pair<T1, T2> lhs, Pair<T1, T2> rhs) {
                  return compareTo(lhs, rhs);
              }
  
          };
  	}