如何在不同.py文件上的Kivy屏幕之间切换

from kivy.app import App
from kivy.uix.screenmanager import ScreenManager

from screen1 import Screen1
from screen2 import Screen2

class MyApp(App):
    def build(self):
        # 创建屏幕管理器
        screen_manager = ScreenManager()

        # 添加屏幕
        screen_manager.add_widget(Screen1(name='screen1'))
        screen_manager.add_widget(Screen2(name='screen2'))

        # 设置初始屏幕
        screen_manager.current = 'screen1'

        return screen_manager

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

from kivy.uix.screenmanager import Screen
from kivy.uix.button import Button

class Screen1(Screen):
    def __init__(self, **kwargs):
        super(Screen1, self).__init__(**kwargs)

        # 定义屏幕布局
        self.add_widget(Button(text='Go to Screen 2', on_release=self.go_to_screen2))

    def go_to_screen2(self, instance):
        # 切换到Screen2
        self.manager.current = 'screen2'

from kivy.uix.screenmanager import Screen
from kivy.uix.button import Button

class Screen2(Screen):
    def __init__(self, **kwargs):
        super(Screen2, self).__init__(**kwargs)

        # 定义屏幕布局
        self.add_widget(Button(text='Go to Screen 1', on_release=self.go_to_screen1))

    def go_to_screen1(self, instance):
        # 切换到Screen1
        self.manager.current = 'screen1'