pub fn send_after<T>(
    period: Duration,
    handle: GenServerHandle<T>,
    message: T::CastMsg,
) -> TimerHandlewhere
    T: GenServer + 'static,pub fn send_after<T>(
    period: Duration,
    handle: GenServerHandle<T>,
    message: T::CastMsg,
) -> TimerHandlewhere
    T: GenServer + 'static,