self.countdown(10)

def countdown(self, remaining=None):
    if remaining is not None:
        self.remaining = remaining
if self.remaining <= 0:
    self.label.configure(text="time's up!")
else:
    self.label.configure(text='%d' % self.remaining)
self.remaining = self.remaining - 1
self.after(1000, self.countdown)
if __name__ == '__main__':
    app = ExampleApp()
app.mainloop()
Сделать таймер обратного отсчета с помощью Python и Tkinter?