code: def register_slo(username, session_key, ticket):
          
          try:
              FederateSLO.objects.create(
                  username=username,
                  session_key=session_key,
                  ticket=ticket
              )
          except IntegrityError:  # pragma: no cover (ignore if the FederateSLO already exists)
              pass
docs: association a ``ticket`` with a (``username``, ``session_key``) for processing later SLO
              request by creating a :class:`cas_server.models.FederateSLO` object.
  
              :param unicode username: A logged user username, with the ``@`` component.
              :param unicode session_key: A logged user session_key matching ``username``.
              :param unicode ticket: A ticket used to authentication ``username`` for the session
                  ``session_key``.