class ViewController:
    def __init__(self):
        self.screen = None  # type: "Adafruit_ST77XX"

    def _add_screen(self, screen):
        self.screen = screen

    def draw(self):
        pass

    def on_load(self):
        pass

    def on_unload(self):
        pass

    def on_up(self):
        pass

    def on_down(self):
        pass

    def on_left(self):
        pass

    def on_right(self):
        pass

    def on_back(self):
        pass

    def on_enter(self):
        pass

    def on_event(self, event):
        pass
