code: function addLinkedStyleSheet(url, deferred) {
          var attributes = {
              type: "text/css",
              rel:  "stylesheet",
              href: url
          };
  
          var $link = $("<link/>").attr(attributes);
  
          if (deferred) {
              $link.on('load', deferred.resolve).on('error', deferred.reject);
          }
  
          $link.appendTo("head");
  
          return $link[0];
      }
docs: Appends a <link> tag to the document's head.
  
  @param {!string} url URL to a style sheet
  @param {$.Deferred=} deferred Optionally check for load and error events
  @return {!HTMLLinkElement} The generated HTML node