code: function(url, win, attributes) {
          var o = {
              id:   Y.guid(),
              type: TYPE_JS
          };
  
          if (attributes) {
              Y.mix(o, attributes);
          }
  
          o.src = url;
  
          return _node("script", o, win);
      }
docs: hash of queues to manage multiple requests
  @property queues
  @private