function changevisible(element){
        var children = element.parentNode.childNodes;
        for(var i= 0; i<children.length;i++){
            if(children[i].nodeName == "DIV"){
                var className = children[i].className;                    
                if(className == "show"){
                    element.className="fold";
                    children[i].className="hidden";
                }
                else{
                    element.className="expend";
                    children[i].className="show";
                }
            }
        }
    }