docs: private int median3(PagesIndex pagesIndex, int a, int b, int c)
      {
          int ab = comparator.compareTo(pagesIndex, a, b);
          int ac = comparator.compareTo(pagesIndex, a, c);
          int bc = comparator.compareTo(pagesIndex, b, c);
          return (ab < 0 ?
                  (bc < 0 ? b : ac < 0 ? c : a) :
                  (bc > 0 ? b : ac > 0 ? c : a));
      }