function close_all_menu(){
		
		for (i=0; i<document.getElementsByTagName("ul").length; i++) {
        		if (document.getElementsByTagName("ul").item(i).className == "sous_menu"){
    				document.getElementsByTagName("ul").item(i).style.display="none";
       		 	}
		}
				
	}
	
	function open_menu(sous_menu) {
		
		close_all_menu();
		document.getElementById(sous_menu).style.display="block";
		
	}