TypeError：'AnchorLayout'对象不可调用kivy python

Question

几天前，代码完美运行。今天，尝试启动程序时出现TypeError。

TypeError: 'AnchorLayout' object is not callable kivy python

怎么了？

class MyApp(App):
    def __init__(self, **kwargs):
        super().__init__(**kwargs)
        self.password = TextInput(text='', password=True, multiline=False, size_hint_y=None)  # Обьявление пароля
        self.username = TextInput(text='', multiline=False, size_hint_y=None)  # Обьявление логина

    @property
    def build(self):
        al: AnchorLayout = AnchorLayout(anchor_x='center',anchor_y='center')

        al.add_widget(Label(text='Login'))

        al.add_widget(self.username)
        al.add_widget(Label(text='Password'))

        al.add_widget(self.password)
        al.add_widget(Button(text='Войти', on_press=self.login))
        return al

    def login(self, instance):
        username = print(self.username.text)
        password = print(self.password.text)
        s = cursor.execute("SELECT password FROM drivers WHERE username='"+str(username)+"'")
        for x in cursor:
            print(x)
        if password == s:
            print('Success')