def global_request(self, kind, data=None, wait=True):
        """
        Make a global request to the remote host.  These are normally
        extensions to the SSH2 protocol.

        :param str kind: name of the request.
        :param tuple data:
            an optional tuple containing additional data to attach to the
            request.
        :param bool wait:
            ``True`` if this method should not return until a response is
            received; ``False`` otherwise.
        :return:
            a `.Message` containing possible additional data if the request was
            successful (or an empty `.Message` if ``wait`` was ``False``);
            ``None`` if the request was denied.
        """
        if wait:
            self.completion_event = threading.Event()
        m = Message()
        m.add_byte(cMSG_GLOBAL_REQUEST)
        m.add_string(kind)
        m.add_boolean(wait)
        if data is not None:
            m.add(*data)
        self._log(DEBUG, 'Sending global request "%s"' % kind)
        self._send_user_message(m)
        if not wait:
            return None
        while True:
            self.completion_event.wait(0.1)
            if not self.active:
                return None
            if self.completion_event.isSet():
                break
        return self.global_response