function $(id) {
    var el = document.getElementById(id);
    
    el.tween = function(prop, _from, _to) {
      var _tweenDuration = 1;
      var tw = new Tween(el.style, prop, Tween.strongEaseOut, _from, _to, _tweenDuration, 'px'); 
      tw.start();
    }   
    
    return el;
    
  }