code: function(data) {
      if (this.app) {
        data._app = this.app;
      }
      if (this.model) {
        data._model = this.model;
      }
      if (this.collection) {
        data._collection = this.collection;
      }
      data._view = this;
      return data;
    }
docs: Add special properties `_app` and `_model` or `_collection` to pass to
  the templates.