如何在kivy screen change中调用类中的def

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

class MyScreenManager(ScreenManager):
    pass

class Screen1(Screen):
    def my_method(self):
        # 在这里编写你的方法逻辑
        pass

class Screen2(Screen):
    pass

class MyApp(App):
    def build(self):
        sm = MyScreenManager()
        sm.add_widget(Screen1(name='screen1'))
        sm.add_widget(Screen2(name='screen2'))
        return sm

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

Button:
    text: 'Call Method'
    on_release: app.root.current_screen.my_method()