docs: public static <T> T median(List<? extends T> data, Comparator<? super T> comparator, int begin, int end) {
      final int length = end - begin;
      assert (length > 0);
      // Integer division is "floor" since we are non-negative.
      final int left = begin + ((length - 1) >> 1);
      quickSelect(data, comparator, begin, end, left);
      return data.get(left);
    }