如何在kivy中使用widget碰撞切换屏幕？

from kivy.app import App
from kivy.uix.screenmanager import ScreenManager, Screen
from kivy.uix.button import Button
from kivy.uix.boxlayout import BoxLayout
from kivy.metrics import sp

class MainScreen(Screen):
    def __init__(self, **kwargs):
        super(MainScreen, self).__init__(**kwargs)
        layout = BoxLayout(orientation='vertical')
        button = Button(text='Click me!', size_hint=(None, None), size=(sp(100), sp(50)))
        button.bind(on_release=self.on_button_release)
        layout.add_widget(button)
        self.add_widget(layout)

    def on_button_release(self, instance):
        # 进行碰撞检测，切换到其他屏幕
        if instance.collide_widget(self.another_widget):
            self.manager.current = 'another'

class AnotherScreen(Screen):
    def __init__(self, **kwargs):
        super(AnotherScreen, self).__init__(**kwargs)
        layout = BoxLayout(orientation='vertical')
        button = Button(text='Go back!', size_hint=(None, None), size=(sp(100), sp(50)))
        button.bind(on_release=self.on_button_release)
        layout.add_widget(button)
        self.add_widget(layout)

    def on_button_release(self, instance):
        # 切换回主屏幕
        self.manager.current = 'main'

class MyApp(App):
    def build(self):
        screen_manager = ScreenManager()
        main_screen = MainScreen(name='main')
        another_screen = AnotherScreen(name='another')
        main_screen.another_widget = another_screen
        another_screen.another_widget = main_screen
        screen_manager.add_widget(main_screen)
        screen_manager.add_widget(another_screen)
        return screen_manager

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