def event_handler(source, evt):
    if (evt == lv.EVENT.CLICKED):
        if (source == btn1):
            print('Clicked')
        elif (evt == lv.EVENT.VALUE_CHANGED):
            print('Toggled')
def event_handler(source, evt):
    if (evt == lv.EVENT.CLICKED):
        if (source == btn1):
            print('Clicked')
        elif (evt == lv.EVENT.VALUE_CHANGED):
            print('Toggled')