我嘗試在用 Tkinter 制作的游戲中添加計時器from tkinter import *timer = 60def startGame(event):    if timer == 60:        countdown()def countdown():    global timer    if timer > 0:        timer -= 1        timeLabel.config(text='Time left:' + str(timer))        timer.after(1000, countdown())window = Tk()timeLabel = Label(window, text='time = 60 sec')entryBox = Entry(window)timeLabel.pack()entryBox.pack()window.bind('<Return>', startGame)entryBox.packentryBox.focus_set()window.mainloop()當您在輸入框中按 Enter 時，計時器應該啟動，但它卻顯示此錯誤Exception in Tkinter callbackTraceback (most recent call last):  File "/usr/lib/python3.6/tkinter/__init__.py", line 1705, in __call__    return self.func(*args)  File "/home/user/PycharmProjects/Game/example.py", line 5, in startGame    countdown()  File "/home/user/PycharmProjects/Game/example.py", line 11, in countdown    timer.after(1000, countdown())AttributeError: 'int' object has no attribute 'after'我嘗試過將計時器轉換為字符串和浮動str(timer).after(1000, countdown())     in line11float(timer).after(1000, countdown())   in line11如果這 3 個屬性（int、str 和 float）不起作用，則與“entry”一起使用?；蛘呷绾螢槲业挠螒蛱砑佑嫊r器？