code: function () {
            var level;
  
            if (index < data.length - 1) {
              level = data[++index];
              Levels.applyToEditor(editor, level, false);
              setDirty(true);
              editor.fire('redo', { level: level });
            }
  
            return level;
          }
docs: Redoes the last action.
  
  @method redo
  @return {Object} Redo level or null if no redo was performed.