'Create a fork of this repository.
:param str organization: (required), login for organization to create
the fork under
:returns: :class:`Repository <Repository>` if successful, else None'

@requires_auth
def create_fork(self, organization=None):

    url = self._build_url(u'forks', base_url=self._api)
    if organization:
        resp = self._post(url, data={u'organization': organization})
    else:
        resp = self._post(url)
    json = self._json(resp, 202)
    return self._instance_or_null(Repository, json)
