def add_hook_pull(self, address, callback):
        """Same as above, but with a PULL socket.
        (e.g good for pushed 'inproc' messages from another thread).
        """
        LOGGER.info("Subscriber adding PULL hook %s", str(address))
        socket = get_context().socket(PULL)
        socket.connect(address)
        self._add_hook(socket, callback)