def METHOD_NAME(self) -> None:
    sm = QStateMachine(self)
    sm.finished.connect(QApplication.quit)
    start = self._build_start_state()
    sm.addState(start)
    exit = self._build_exit_state()
    sm.addState(exit)
    # start.addTransition(self.button.clicked, exit)
    sm.setInitialState(start)
    sm.start()
    self.state_machine = sm