code: func NewClient(apiKey string, secretKey string) (*Client, error) {
  	if apiKey == "" {
  		return nil, fmt.Errorf("CloudXNS: credentials missing: apiKey")
  	}
  
  	if secretKey == "" {
  		return nil, fmt.Errorf("CloudXNS: credentials missing: secretKey")
  	}
  
  	return &Client{
  		apiKey:     apiKey,
  		secretKey:  secretKey,
  		HTTPClient: &http.Client{},
  		BaseURL:    defaultBaseURL,
  	}, nil
  }
docs: // NewClient creates a CloudXNS client