function choose(menu) {
    if (document.getElementById) {
        var curr = document.getElementById(menu);
        var elements = document.getElementById("menu").getElementsByTagName("ul");
        if(curr.style.display == "none"){
			for (var i=0; i<elements.length; i++){
				elements[i].style.display = "none";
			}
			curr.style.display = "block";
		}else{
			curr.style.display = "none";
		}
    }
}