如何使用屏幕上的类继承在kivy中创建按钮

from kivy.app import App
from kivy.uix.button import Button
from kivy.uix.boxlayout import BoxLayout

class MyButton(Button):
    def __init__(self, **kwargs):
        super(MyButton, self).__init__(**kwargs)
        # 自定义按钮的一些属性和行为

class MyBoxLayout(BoxLayout):
    def __init__(self, **kwargs):
        super(MyBoxLayout, self).__init__(**kwargs)
        self.orientation = 'vertical'
        self.add_widget(MyButton(text='按钮1'))
        self.add_widget(MyButton(text='按钮2'))

class MyApp(App):
    def build(self):
        return MyBoxLayout()

if __name__ == '__main__':
    MyApp().run()