code: def get(self, request, *args, **kwargs):
          
          service = request.GET.get('service')
          renew = to_bool(request.GET.get('renew'))
          gateway = to_bool(request.GET.get('gateway'))
  
          if renew:
              logger.debug("Renew request received by credential requestor")
          elif gateway and service:
              logger.debug("Gateway request received by credential requestor")
              if is_authenticated(request.user):
                  st = ServiceTicket.objects.create_ticket(service=service, user=request.user)
                  if self.warn_user():
                      return redirect('cas_warn', params={'service': service, 'ticket': st.ticket})
                  return redirect(service, params={'ticket': st.ticket})
              else:
                  return redirect(service)
          elif is_authenticated(request.user):
              if service:
                  logger.debug("Service ticket request received by credential requestor")
                  st = ServiceTicket.objects.create_ticket(service=service, user=request.user)
                  if self.warn_user():
                      return redirect('cas_warn', params={'service': service, 'ticket': st.ticket})
                  return redirect(service, params={'ticket': st.ticket})
              else:
                  msg = _("You are logged in as %s") % request.user
                  messages.success(request, msg)
          return super(LoginView, self).get(request, *args, **kwargs)
docs: (2.1) As a credential requestor, /login accepts three optional
          parameters:
  
          1. ``service``: the identifier of the application the client is
             accessing. We assume this identifier to be a URL.
          2. ``renew``: requires a client to present credentials
             regardless of any existing single sign-on session.
          3. ``gateway``: causes the client to not be prompted for
             credentials. If a single sign-on session exists the user
             will be logged in and forwarded to the specified service.
             Otherwise, the user remains logged out and is forwarded to
             the specified service.