quota/quota.go
func (s *QuotaService) Inc(appName string, quantity int) error {
	quota, err := s.Storage.Get(appName)
	if err != nil {
		return err
	}
	err = s.checkLimit(quota, quantity)
	if err != nil {
		return err
	}
	return s.Storage.Inc(appName, quantity)
}
func (s *QuotaService) Inc(appName string, quantity int) error {
	quota, err := s.Storage.Get(appName)
	if err != nil {
		return err
	}
	err = s.checkLimit(quota, quantity)
	if err != nil {
		return err
	}
	return s.Storage.Inc(appName, quantity)
}
// Inc implements Inc method from QuotaService interface