code: func SAMLUnauthorized(loginURL string) func(error) *ErrorResource {
  	return func(reason error) *ErrorResource {
  		if reason == nil {
  			reason = errors.New("Request not authenticated, API token is missing, invalid or expired")
  		}
  
  		return &ErrorResource{
  			Status:  http.StatusUnauthorized,
  			ID:      "saml_unauthorized",
  			Message: fmt.Sprintf("%s. Login at %s", reason, loginURL),
  		}
  	}
  }
docs: // SAMLUnauthorized can be used in place of Unauthorized to return a link to
  // login via SAML.