How to use the @esri/arcgis-rest-portal.createFolder function in @esri/arcgis-rest-portal

return new Promise((resolve, reject) => {
    const folderTitle: string = generalHelpers.getUniqueTitle(
      title,
      templateDictionary,
      "user.folders"
    );
    const folderCreationParam = {
      title: folderTitle,
      authentication: authentication
    };
    portal.createFolder(folderCreationParam).then(
      ok => resolve(ok),
      err => {
        reject(err);
      }
    );
  });
}