function initNodes(){
        var uls = document.getElementsByTagName("ul");
        var i;
            for(i = 0; i < uls.length; i++)
                if(uls[i].id != "root")
                    uls[i].style.display = "none";
        }

        function clickNode(id){
        var node = document.getElementById(id);
        if (node){ 
            if(node.style.display == "none")
                node.style.display = "block";
            else
                node.style.display = "none";
        }
        return false;
        }