errgroup

type ErrGroup interface {
	// Go calls the given function in a new goroutine.
	//
	// The first call to return a non-nil error cancels the group; its error will be
	// returned by Wait.
	Go(fn func(ctx context.Context) error)

	// GOMAXPROCS set max goroutine to work.
	GOMAXPROCS(n int)

	// Wait blocks until all function calls from the Go method have returned, then
	// returns the first non-nil error (if any) from them.
	Wait() error
}