 modelForElement(el);
       *   if (model.index < 10) {
       *     model.set('item.checked', true);
       *   }
       *
       * @memberof Polymer.Templatize
       * @param {HTMLTemplateElement} template The model will be returned for
       *   elements stamped from this template
       * @param {HTMLElement} el Element for which to return a template model.
       * @return {TemplateInstanceBase} Template instance representing the
       *   binding scope for the element
       */
      modelForEleme