How to use the whitenoise.responders.NotARegularFileError function in whitenoise

regular file
        """
        try:
            stat_result = stat_function(path)
        except KeyError:
            raise MissingFileError(path)
        except OSError as e:
            if e.errno in (errno.ENOENT, errno.ENAMETOOLONG):
                raise MissingFileError(path)
            else:
                raise
        if not stat.S_ISREG(stat_result.st_mode):
            if stat.S_ISDIR(stat_result.st_mode):
                raise IsDirectoryError(u"Path is a directory: {0}".format(path))
            else:
                raise NotARegularFileError(u"Not a regular file: {0}".format(path))
        return stat_result

class Redirect(object):
    def __init__(self, location, headers=None):
        headers = list(headers.items()) if headers else []
        headers.append(("Location", quote(location.encode("utf8"))))
        self.response = Response(HTTPStatus.FOUND, headers, None)

    def get_response(self, method, request_headers):
        return self.response


class NotARegularFileError(Exception):
    pass


class MissingFileError(NotARegularFileError):
    pass


class IsDirectoryError(MissingFileError):
    pass


class FileEntry(object):
    def __init__(self, path, stat_cache=None):
        stat_function = os.stat if stat_cache is None else stat_cache.__getitem__
        self.stat = self.stat_regular_file(path, stat_function)
        self.path = path

    @staticmethod
    def stat_regular_file(path, stat_function):
        """