code: function (index, count) {
          index = index || 0;
          count = count || this.length;
          validateListIndex(this, index + count - 1);
  
          var arr = this.slice(index, index + count).reverse(),
              len = arr.length;
  
          while (len-- > 0) {
              this[len + index] = arr[len];
          }
  
          return this;
      }
docs: Reverses the order of the elements in the specified range.
  @param {Number=} index The zero-based starting index of the range to reverse.
  @param {Number=} count The number of elements in the range to reverse.