def sendGlobalRequest(self, request, data, wantReply=0):
        """
        Send a global request for this connection.  Current this is only used
        for remote->local TCP forwarding.

        @type request:      L{bytes}
        @type data:         L{bytes}
        @type wantReply:    L{bool}
        @rtype              C{Deferred}/L{None}
        """
        self.transport.sendPacket(MSG_GLOBAL_REQUEST,
                                  common.NS(request)
                                  + (wantReply and b'\xff' or b'\x00')
                                  + data)
        if wantReply:
            d = defer.Deferred()
            self.deferreds['global'].append(d)
            return d

        Send a global request for this connection.  Current this is only used
        for remote->local TCP forwarding.

        @type request:      L{bytes}
        @type data:         L{bytes}
        @type wantReply:    L{bool}
        @rtype              C{Deferred}/L{None}
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/conch/ssh/connection.py