changeAwaiting

        fn changeAwaiting(
            cancel_status: *CancelStatus,
            old_awaiting: Awaiting,
            new_awaiting: Awaiting,
        ) bool {
            const old_cancel_status = @atomicRmw(CancelStatus, cancel_status, .Add, .{
                .requested = false,
                .awaiting = new_awaiting.subWrap(old_awaiting),
            }, .monotonic);
            assert(old_cancel_status.awaiting == old_awaiting);
            return old_cancel_status.requested;
        }