def __missing__(self, key):
        if self.default_factory is None:
            raise KeyError(key)
        else:
            ret = self[key] = self.default_factory(name=key)
            return ret
def _swdb_group_install(self, group_id, pkg_types, pkgs):
        swdb_group = self._create_swdb_group(group_id, pkg_types, pkgs)

        if swdb_group is not None:
            self._base.history.group.install(swdb_group)