code: def check_lt(self):
          
          # save LT for later check
          lt_valid = self.request.session.get('lt', [])
          lt_send = self.request.POST.get('lt')
          # generate a new LT (by posting the LT has been consumed)
          self.gen_lt()
          # check if send LT is valid
          if lt_send not in lt_valid:
              return False
          else:
              self.request.session['lt'].remove(lt_send)
              # we need to redo the affectation for django to detect that the list has changed
              # and for its new value to be store in the session
              self.request.session['lt'] = self.request.session['lt']
              return True
docs: Check is the POSTed LoginTicket is valid, if yes invalide it
  
              :return: ``True`` if the LoginTicket is valid, ``False`` otherwise
              :rtype: bool