code: def key(self, id_num):
          
          json = None
          if int(id_num) > 0:
              url = self._build_url('keys', str(id_num), base_url=self._api)
              json = self._json(self._get(url), 200)
          return Key(json, self) if json else None
docs: Get the specified deploy key.
  
          :param int id_num: (required), id of the key
          :returns: :class:`Key <github3.users.Key>` if successful, else None