/* Show menu level */
function showLevel(ulId) {
  var ul = document.getElementById(ulId);
  if (ul != null) {
      var elements = ul.childNodes;
      for (var i = 0; i < elements.length; i++) {
          if(elements[i].tagName == 'LI') {
            elements[i].style.display = "block";
          }
      }
  }
}

/* Hide menu level */
function hideLevel(ulId) {
  var ul = document.getElementById(ulId);
  if (ul != null) {
      var elements = ul.childNodes;
      for (var i = 0; i < elements.length; i++) {
          if(elements[i].tagName == 'LI') {
            elements[i].style.display = "none";
          }
      }
  }
}