}
	}

	return nil
}

// Concurrency helpers

type concErr struct {
	errMap     map[string]error
	summaryErr error
}

func (c concErr) Error() string {
	if c.summaryErr != nil {
		return c.summaryErr.Error()
	}
	return "<nil>"
}

func (c concErr) Unwrap() error {
	return c.summaryErr
}