code: func (b *backendInstance) addTimeout(
  	ctx context.Context) (context.Context, context.CancelFunc) {
  	if ctx == nil {
  		ctx = context.Background()
  	}
  	return context.WithTimeout(ctx,
  		time.Duration(b.cfg.Timeout)*time.Millisecond)
  }
docs: // addTimeout adds timeout to context.