async def METHOD_NAME(self) -> None:
    """
    Represents one loop of the service.
    Users should override this method.
    To actually run the service once, call `LoopService().start(loops=1)`
    instead of `LoopService().run_once()`, because this method will not invoke setup
    and teardown methods properly.
    """
    raise NotImplementedError("LoopService subclasses must implement this method.")