context

type MContext interface {
	WithTimeout(timeout time.Duration) (MContext, context.CancelFunc)
	WithCancel() (MContext, context.CancelFunc)

	// goroutine
	Go(exec func())
	WaitGoroutine()

	// basic
	Done() <-chan struct{}
	Deadline() (time.Time, bool)
	Value(key interface{}) interface{}
	Err() error
}