class ScreenManager:
    VALID_SCREENS = ("dashboard", "battery", "temps", "power", "system")

    def __init__(self):
        self.current_screen = "dashboard"

    def go_to(self, screen_name):
        if screen_name not in self.VALID_SCREENS:
            raise ValueError(f"Invalid screen: {screen_name}")

        self.current_screen = screen_name

    def next_screen(self):
        current_index = self.VALID_SCREENS.index(self.current_screen)
        next_index = (current_index + 1) % len(self.VALID_SCREENS)
        self.current_screen = self.VALID_SCREENS[next_index]

    def previous_screen(self):
        current_index = self.VALID_SCREENS.index(self.current_screen)
        previous_index = (current_index - 1) % len(self.VALID_SCREENS)
        self.current_screen = self.VALID_SCREENS[previous_index]