':calls: `POST /repos/:owner/:repo/git/refs <http://developer.github.com/v3/git/refs>`_
:param ref: string
:param sha: string
:rtype: :class:`github.GitRef.GitRef`'

def create_git_ref(self, ref, sha):

    assert isinstance(ref, (str, unicode)), ref
    assert isinstance(sha, (str, unicode)), sha
    post_parameters = {'ref': ref, 'sha': sha}
    (headers, data) = self._requester.requestJsonAndCheck('POST', (self.url + '/git/refs'), input=post_parameters)
    return github.GitRef.GitRef(self._requester, headers, data, completed=True)
