code: func GetFromResponse(resp *http.Response) (string, error) {
  	if resp == nil {
  		return "", errors.New("nil response")
  	}
  
  	nonce := resp.Header.Get("Replay-Nonce")
  	if nonce == "" {
  		return "", fmt.Errorf("server did not respond with a proper nonce header")
  	}
  
  	return nonce, nil
  }
docs: // GetFromResponse Extracts a nonce from a HTTP response.