'Retrieve the gist using the specified id number.
:param int id_num: (required), unique id of the gist
:returns: :class:`Gist <github3.gists.Gist>`'

def gist(self, id_num):

    url = self._build_url(u'gists', str(id_num))
    json = self._json(self._get(url), 200)
    return self._instance_or_null(Gist, json)
