code: function sortCssClasses(attrs) {
      /**
       * Sorts the given CSS class attribute
       * @param {String} cssClasses
       * @returns {String}
       */
      function _sortCssClassesValues(cssClasses) {
          var classList = (cssClasses || '').split(' ');
  
          return _(classList)
              .filter()
              .uniq()
              .sort()
              .join(' ');
      }
  
      var classIndexes = _getIndexesInArray(attrs, 'class');
  
      _.forEach(classIndexes, function (index) {
          attrs[index].value = _sortCssClassesValues(attrs[index].value);
      });
  
      return attrs;
  }
docs: Sorts values of the attribute 'class'
  @param {Array} attrs
  @returns {Array}