var string;
function apri(nodo){
		for (i = 0; i < nodo.childNodes.length; i++) {
			if ((node = nodo.childNodes[i]).nodeName.toLowerCase() == "ul") {
				node.style.visibility="visible";
			}
		}
		if (document.getElementById('terzoLivelloVisibile') != null){
    		document.getElementById('terzoLivelloVisibile').style.visibility="hidden";
		}
}	

function chiudi(nodo){
		for (i = 0; i < nodo.childNodes.length; i++) {
			if ((node = nodo.childNodes[i]).nodeName.toLowerCase() == "ul") {
			node.style.visibility="hidden";
			}
		}
		if (document.getElementById('terzoLivelloVisibile') != null)
		{
			document.getElementById('terzoLivelloVisibile').style.visibility="visible";
		}
}