var el = document.getElementsByTagName("span");
//var melo = document.getElementById("melodia");
//var el = melo.getElementsSByTagName("span");
var att = 0; 
function tog () {
    for ( ind = 0; ind < el.length; ind++ ) { 
        el.item(ind).style.display = "none"; 
    }
    if ( att < el.length - 1 ) { att = att + 1; } else { att = 0; }
    el.item(att).style.display = "inline";  
}
function ora () {
    for ( ind = 0; ind < el.length; ind++ ) { 
        el.item(ind).style.display = "none";
    }
    el.item(0).style.display = "inline"; 
}