(funciton($){
                $.fn.extend({
                    "f":function(){
                        $("li").each(function(index){
                            $(this).bind("mouseover",function(){
                                $(this).className="a";
                            });
                            $(this).bind("mouseout",function(){
                                $(this).className="";
                            });
                        })
                    }
                })
            })(jQuery);
            $(function(){
                 $("ul").f();
            })

这是哪里搞错了？