docs: private static void insertionSort(int[] data, final int start, final int end, IntComparator comp) {
      // Classic insertion sort.
      for(int i = start + 1; i < end; i++) {
        final int cur = data[i];
        int j = i - 1;
        while(j >= start) {
          final int pre = data[j];
          if(comp.compare(cur, pre) >= 0) {
            break;
          }
          data[j + 1] = pre;
          --j;
        }
        data[j + 1] = cur;
      }
    }