Tree with different children widget types

dojo.require("dijit.Tree");
dojo.extend(dijit.Tree, {
    childWidgetType: "dijit._TreeNode",
    _createTreeNode: function(args){
         if (typeof this.childWidgetType == 'string') {
             this.childWidgetType = dojo.getObject(this.childWidgetType);
         }
         return new this.childWidgetType(args);
    }
});