def setup_button(): global plus global minus global enter GPIO.setup(PLUS_BUTTON, GPIO.IN, GPIO.PUD_UP) GPIO.setup(MINUS_BUTTON, GPIO.IN, GPIO.PUD_UP) GPIO.setup(ENTER_BUTTON, GPIO.IN, GPIO.PUD_UP) plus = Button(PLUS_BUTTON) minus = Button(MINUS_BUTTON) enter = Button(ENTER_BUTTON) plus.addXButtonListener(onButtonEvent_plus) minus.addXButtonListener(onButtonEvent_minus) enter.addXButtonListener(onButtonEvent_enter)