code: func NewDNSProviderConfig(config *Config) (*DNSProvider, error) {
  	if config == nil {
  		return nil, errors.New("googlecloud: the configuration of the DNS provider is nil")
  	}
  	if config.HTTPClient == nil {
  		return nil, fmt.Errorf("googlecloud: unable to create Google Cloud DNS service: client is nil")
  	}
  
  	svc, err := dns.NewService(context.Background(), option.WithHTTPClient(config.HTTPClient))
  	if err != nil {
  		return nil, fmt.Errorf("googlecloud: unable to create Google Cloud DNS service: %v", err)
  	}
  
  	return &DNSProvider{config: config, client: svc}, nil
  }
docs: // NewDNSProviderConfig return a DNSProvider instance configured for Google Cloud DNS.