def get_git_ref(self, ref):
        """
        :calls: `GET /repos/:owner/:repo/git/refs/:ref <http://developer.github.com/v3/git/refs>`_
        :param ref: string
        :rtype: :class:`github.GitRef.GitRef`
        """
        prefix = "/git/refs/"
        if not self._requester.FIX_REPO_GET_GIT_REF:
            prefix = "/git/"
        assert isinstance(ref, (str, unicode)), ref
        headers, data = self._requester.requestJsonAndCheck(
            "GET",
            self.url + prefix + ref
        )
        return github.GitRef.GitRef(self._requester, headers, data, completed=True)