PendingTask

    const PendingTask = union(enum) {
        nothing,
        await: *Fiber,
        activate: c.dispatch.object_t,
        @"resume": c.dispatch.object_t,
        group_await: Group,
        group_cancel: Group,
        mutex_wait: *Mutex.Waiter,
        futex_wait: *Futex.Waiter,
        futex_wake: *Futex.Waker,
        sleep_wait: *SleepWaiter,
        after: c.dispatch.time_t,
        destroy,
        exit,
    }