// defined in context.go, that supports registering AfterFuncs.
type afterFuncContext struct {
	mu         sync.Mutex
	afterFuncs map[*byte]func()
	done       chan struct{}
	err        error
}

func newAfterFuncContext() context.Context {
	return &afterFuncContext{}
}

func (c *afterFuncContext) Deadline() (time.Time, bool) {
	return time.Time{}, false
}

func (c *afterFuncContext) Done() <-chan struct{} {
	c.mu.Lock()