class BaseRouter:
    def post_message(self, namespace: bytes, topic: bytes, kind: bytes, body: bytes) -> None:
        raise NotImplementedError


class StdOutRouter(BaseRouter):
    def post_message(self, namespace: bytes, topic: bytes, kind: bytes, body: bytes) -> None:
        print(f'ns={namespace.decode()},t={topic.decode()},k={kind.decode()}  {body.decode()}')