How to use the @uifabric/example-app-base/lib/index2.NavSortType.categories function in @uifabric/example-app-base

className={styles.searchBox}
          placeholder={`Search ${pageTitle}`}
          value={searchQuery}
          onChange={this._onSearchQueryChanged}
          onClick={this._onSearchBoxClick}
          underlined={true}
          styles={searchBoxStyles}
        />

public constructor(props: INavProps) {
    super(props);

    this._localItems = !!window.localStorage
      ? {
          defaultSortState: NavSortType[localStorage.getItem('defaultSortState') as keyof typeof NavSortType]
        }
      : {};

    this.state = {
      defaultSortState: this._localItems.defaultSortState ? NavSortType[this._localItems.defaultSortState] : NavSortType.categories,
      searchQuery: '',
      sortState: this._localItems.defaultSortState ? NavSortType[this._localItems.defaultSortState] : NavSortType.categories
    };
  }

private _setSortTypeCategories = (): void => {
    this.setState(
      {
        defaultSortState: NavSortType.categories,
        sortState: NavSortType.categories
      },
      () => {
        localStorage.setItem('defaultSortState', NavSortType[NavSortType.categories]);
      }
    );
  };

public constructor(props: INavProps) {
    super(props);

    this._localItems = !!window.localStorage
      ? {
          defaultSortState: NavSortType[localStorage.getItem('defaultSortState') as keyof typeof NavSortType]
        }
      : {};

    this.state = {
      defaultSortState: this._localItems.defaultSortState ? NavSortType[this._localItems.defaultSortState] : NavSortType.categories,
      searchQuery: '',
      sortState: this._localItems.defaultSortState ? NavSortType[this._localItems.defaultSortState] : NavSortType.categories
    };
  }

() => {
        localStorage.setItem('defaultSortState', NavSortType[NavSortType.categories]);
      }
    );

private _setSortTypeCategories = (): void => {
    this.setState(
      {
        defaultSortState: NavSortType.categories,
        sortState: NavSortType.categories
      },
      () => {
        localStorage.setItem('defaultSortState', NavSortType[NavSortType.categories]);
      }
    );
  };