code: def get_cas_client(self, request, provider, renew=False):
          
          # compute the current url, ignoring ticket dans provider GET parameters
          service_url = utils.get_current_url(request, {"ticket", "provider"})
          self.service_url = service_url
          return CASFederateValidateUser(provider, service_url, renew=renew)
docs: return a CAS client object matching provider
  
              :param django.http.HttpRequest request: The current request object
              :param cas_server.models.FederatedIendityProvider provider: the user identity provider
              :return: The user CAS client object
              :rtype: :class:`federate.CASFederateValidateUser
                  <cas_server.federate.CASFederateValidateUser>`