func (s *Service) ExtendsServicePrefix() string {
	if dotIndex := strings.Index(s.Extends, "."); dotIndex > 0 {
		return s.ExtendsPrefix
	}
	return ""
}
func (s *Service) ExtendsServicePrefix() string {
	if dotIndex := strings.Index(s.Extends, "."); dotIndex > 0 {
		return s.ExtendsPrefix
	}
	return ""
}
// ExtendsServicePrefix returns a package selector (if any) for the extended service.