How to use the powerbi-models.LayoutType function in powerbi-models

hasLayout(layoutType): Promise {
    if (utils.isRDLEmbed(this.report.config.embedUrl)) {
      return Promise.reject(errors.APINotSupportedForRDLError);
    }

    let layoutTypeEnum = models.LayoutType[layoutType];
    return this.report.service.hpm.get(`/report/pages/${this.name}/layoutTypes/${layoutTypeEnum}`, { uid: this.report.config.uniqueId }, this.report.iframe.contentWindow)
      .then(response => response.body,
      response => {
        throw response.body;
      });
  }
}