code: func NewClient(region string, auth Auth, httpClient *http.Client) (*Client, error) {
  	if httpClient == nil {
  		httpClient = &http.Client{}
  	}
  
  	c := &Client{httpClient: httpClient}
  
  	c.endpoint = fmt.Sprintf(identityBaseURL, region)
  
  	identity, err := c.getIdentity(auth)
  	if err != nil {
  		return nil, fmt.Errorf("failed to login: %v", err)
  	}
  
  	c.token = identity.Access.Token.ID
  	c.endpoint = fmt.Sprintf(dnsServiceBaseURL, region)
  
  	return c, nil
  }
docs: // NewClient returns a client instance logged into the ConoHa service.