code: function(html, element) {
        var template = document.createElement('template');
        template.innerHTML = html;
        var fragment = this.instanceTemplate(template);
        if (element) {
          element.textContent = '';
          element.appendChild(fragment);
        }
        return fragment;
      }
docs: Inject HTML which contains markup bound to this element into
  a target element (replacing target element content).
  
  @param String html to inject
  @param Element target element