clock

type Clock interface {
	Now() time.Time
	Since(t time.Time) time.Duration
	Until(t time.Time) time.Duration

	Sleep(d time.Duration)

	Timer(d time.Duration) Timer
	After(d time.Duration) <-chan time.Time
	AfterFunc(d time.Duration, f func()) Timer

	Ticker(d time.Duration) Ticker

	WithDeadline(parent context.Context, deadline time.Time) (context.Context, context.CancelFunc)
	WithTimeout(parent context.Context, timeout time.Duration) (context.Context, context.CancelFunc)
}

type Ticker interface {
	C() <-chan time.Time
	Stop()
	Reset(d time.Duration)
}

type Timer interface {
	C() <-chan time.Time
	Stop() bool
	Reset(d time.Duration) bool
}