if s.Start == nil || s.End == nil {
		return nil
	}
	if *s.Start > *s.End {
		return errors.New("ScanRange: Start cannot be after end")
	}
	return nil
}

// StartLen returns start offset plus length from range.
func (s *ScanRange) StartLen() (start, length int64, err error) {
	if s == nil {
		return 0, -1, nil
	}
	err = s.Validate()
	if err != nil {
		return 0, 0, err
	}