':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):

    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)
