def _open_readable(self, namespace, name):
        ns = self._store.get(namespace, None)
        if ns is None:
            raise NamespaceNotFoundError('Unknown namespace %r' % namespace)

        server_sg = ns.get(name, None)
        if server_sg is None:
            raise StreamNotFoundError('Unknown stream %r' % name)

        sg = IMStreamGroup(server_sg)
        return defer.succeed(sg)
dataset/ETHPy150Open arkadini/twimp/twimp/server/inmemory.py/IMServer._open_readable/original