    *
       * @param {HTMLTemplateElement} template Template to prepare
       * @param {boolean=} mutableData When `true`, the generated class will skip
       *   strict dirty-checking for objects and arrays (always consider them to
       *   be "dirty"). Defaults to false.
       */
      templatize(template, mutableData) {
        this._templatizerTemplate = template;
        this.ctor = Polymer.Templatize.templatize(template, this, {
          mutableData: Boolean(mutableData),
          parentModel: