code: func (service *Service) getSessionKey(request *http.Request) (sessionKey string, err error) {
  	loginSession, err := service.GetSession(request, SessionLogin, "loginsession")
  	if err != nil {
  		log.Error(err)
  		return
  	}
  	savedSessionKey := loginSession.Values["sessionkey"]
  	if savedSessionKey != nil {
  		sessionKey, _ = savedSessionKey.(string)
  	}
  	return
  }
docs: //getSessionKey returns an the login session key, or an empty string if there is none