code: def asset(self, id):
          
          data = None
          if int(id) > 0:
              url = self._build_url('releases', 'assets', str(id),
                                    base_url=self._api)
              data = self._json(self._get(url, headers=Release.CUSTOM_HEADERS),
                                200)
          return Asset(data, self) if data else None
docs: Returns a single Asset.
  
          :param int id: (required), id of the asset
          :returns: :class:`Asset <github3.repos.release.Asset>`