function fetch_object(idname) { 
 	var my_obj = document.getElementById(idname); return my_obj; 
} 
function toggle_nav(obj) { 
 	for (i = 1; i<= 5; i++ ) { 
		var sub_nav = fetch_object("sub_nav_" + i); 
		var sub_nav_index = fetch_object("sub_nav_0"); 
		sub_nav_index.style.display = "none"; 
		if (obj == i) { sub_nav.style.display = "block"; } else { sub_nav.style.display = "none"; } 
	} 
}