docs: private static void insertionSort(ArrayModifiableDBIDs data, Comparator<? super DBIDRef> comparator, int start, int end, DBIDArrayIter iter1, DBIDArrayIter iter2) {
      for(int i = start + 1; i < end; i++) {
        for(int j = i; j > start; j--) {
          if(comparator.compare(iter1.seek(j - 1), iter2.seek(j)) <= 0) {
            break;
          }
          data.swap(j, j - 1);
        }
      }
    }