How to use the pyvirtualdisplay.xauth.is_installed function in PyVirtualDisplay

def test_xauth():
    """
    Test that a Xauthority file is created.
    """
    if not xauth.is_installed():
        print("This test needs xauth installed")
        return
    old_xauth = os.getenv("XAUTHORITY")
    display = Display(visible=False, use_xauth=True)
    display.start()
    new_xauth = os.getenv("XAUTHORITY")

    assert new_xauth is not None
    assert os.path.isfile(new_xauth)
    filename = os.path.basename(new_xauth)
    assert filename.startswith("PyVirtualDisplay.")
    assert filename.endswith("Xauthority")

    display.stop()
    assert old_xauth == os.getenv("XAUTHORITY")
    assert not os.path.isfile(new_xauth)

self.display = None
        self._is_started = False

        helptext = get_helptext(program)
        self._has_displayfd = "-displayfd" in helptext
        if not self._has_displayfd:
            log.debug("-displayfd flag is missing.")
        # if check_startup and not has_displayfd:
        #     check_startup = False
        #     log.warning(
        #         program
        #         + " -displayfd flag is not supported, 'check_startup' parameter has been disabled"
        #     )
        self._check_flags(helptext)

        if use_xauth and not xauth.is_installed():
            raise xauth.NotFoundError()

        self._use_xauth = use_xauth
        self._old_xauth = None
        self._xauth_filename = None
        # self.check_startup = check_startup