Scene = ref object of RootObj
  manager*: SceneManager

SceneManager = ref SceneManagerObj

proc set_scene(sm: SceneManager; scene: Scene) {.raises: [Exception],
    tags: [RootEffect].}

proc newSceneManager(first_scene: Scene = nil): SceneManager {.raises: [Exception],
    tags: [RootEffect].}

method enter(self: Scene) {.base, raises: [], tags: [].}

method leave(self: Scene) {.base, raises: [], tags: [].}

method handle(self: Scene; event: Event) {.base, raises: [], tags: [].}

method update(self: Scene; t, dt: float) {.base, raises: [], tags: [].}

method draw(self: Scene) {.base, raises: [], tags: [].}