docs: @SuppressWarnings("unchecked")
      public static <T extends Comparable<? super T>> void mergeSort( T[] arr )
      {
          /*if ( arr.length < 15 ) {
              insertionSort( arr );
              return;
          }*/
          
          T[] tmpArr = (T[]) new Comparable[arr.length];
          
          mergeSort(arr, tmpArr, 0, arr.length - 1);
      }