def become_monitor(self, rules) :
        "turns the connection into one that can only receive monitoring messages."
        message = Message.new_method_call \
          (
            destination = DBUS.SERVICE_DBUS,
            path = DBUS.PATH_DBUS,
            iface = DBUS.INTERFACE_MONITORING,
            method = "BecomeMonitor"
          )
        message.append_objects("asu", (list(format_rule(rule) for rule in rules)), 0)
        self.send(message)
turns the connection into one that can only receive monitoring messages.