:calls: `GET /repos/:owner/:repo/:archive_format/:ref <http://developer.github.com/v3/repos/contents>`_
        :param archive_format: string
        :param ref: string
        :rtype: string

def get_archive_link(self, archive_format, ref=github.GithubObject.NotSet):
        """
        :calls: `GET /repos/:owner/:repo/:archive_format/:ref <http://developer.github.com/v3/repos/contents>`_
        :param archive_format: string
        :param ref: string
        :rtype: string
        """
        assert isinstance(archive_format, (str, unicode)), archive_format
        assert ref is github.GithubObject.NotSet or isinstance(ref, (str, unicode)), ref
        url = self.url + "/" + archive_format
        if ref is not github.GithubObject.NotSet:
            url += "/" + ref
        headers, data = self._requester.requestJsonAndCheck(
            "GET",
            url
        )
        return headers["location"]