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

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