code: function(isSorted) {
      var result = [];
      var length = this.length;
  
      if (!length) {
        return result;
      }
  
      result[0] = this[0];
      var i = 1;
  
      if (isSorted) {
        for (; i < length; i++) {
          if (this[i] !== this[i - 1]) {
            result.push(this[i]);
          }
        }
      } else {
        for (; i < length; i++) {
          if (result.indexOf(this[i]) < 0) {
            result.push(this[i]);
          }
        }
      }
  
      return result;
    }
docs: Returns a duplicate-free clone of the array.
  
  @function Array#unique
  @param {boolean} [isSorted=false] - If the array's contents are sorted and this is set to `true`,
  a faster algorithm will be used to create the unique array.
  @returns {Array} The new, duplicate-free array.
  
  @example
  // Unsorted
  [4, 2, 3, 2, 1, 4].unique();
  // -> [4, 2, 3, 1]
  
  // Sorted
  [1, 2, 2, 3, 4, 4].unique();
  // -> [1, 2, 3, 4]
  
  [1, 2, 2, 3, 4, 4].unique(true);
  // -> [1, 2, 3, 4] (but faster than the previous example)