How to use the djangosaml2.signals.post_authenticated function in djangosaml2

return login_failed(e.message)
        if user is None:
            return login_failed(_('SAML2 authentication failed.'))

        registration_method = settings.WALDUR_AUTH_SAML2.get('name', 'saml2')
        if user.registration_method != registration_method:
            user.registration_method = registration_method
            user.save(update_fields=['registration_method'])

        # required for validating SAML2 logout requests
        auth.login(request, user)
        _set_subject_id(request.session, session_info['name_id'])
        logger.debug('User %s authenticated via SSO.', user)

        logger.debug('Sending the post_authenticated signal')
        post_authenticated.send_robust(sender=user, session_info=session_info)
        token = self.refresh_token(user)

        logger.info(
            'Authenticated with SAML token. Returning token for successful login of user %s',
            user,
        )
        event_logger.saml2_auth.info(
            'User {user_username} with full name {user_full_name} logged in successfully with SAML2.',
            event_type='auth_logged_in_with_saml2',
            event_context={'user': user},
        )
        return login_completed(token.key, 'saml2')

user = auth.authenticate(request=request,
                                 session_info=session_info,
                                 attribute_mapping=attribute_mapping,
                                 create_unknown_user=create_unknown_user)
        if user is None:
            logger.warning("Could not authenticate user received in SAML Assertion. Session info: %s", session_info)
            return fail_acs_response(request, exception=PermissionDenied('No user could be authenticated.'))

        auth.login(self.request, user)
        _set_subject_id(self.request.session, session_info['name_id'])
        logger.debug("User %s authenticated via SSO.", user)
        logger.debug('Sending the post_authenticated signal')

        # post_authenticated.send_robust(sender=user, session_info=session_info)
        # https://github.com/knaperek/djangosaml2/issues/117
        post_authenticated.send_robust(sender=user.__class__,
                                       instance=user,
                                       session_info=session_info,
                                       request=request)
        self.customize_session(user, session_info)

        relay_state = self.build_relay_state()
        custom_redirect_url = self.custom_redirect(user, relay_state, session_info)
        if custom_redirect_url:
            return HttpResponseRedirect(custom_redirect_url)
        relay_state = validate_referral_url(request, relay_state)
        logger.debug('Redirecting to the RelayState: %s', relay_state)
        return HttpResponseRedirect(relay_state)

logger.debug('Trying to authenticate the user. Session info: %s', session_info)
    user = auth.authenticate(request=request,
                             session_info=session_info,
                             attribute_mapping=attribute_mapping,
                             create_unknown_user=create_unknown_user)
    if user is None:
        logger.warning("Could not authenticate user received in SAML Assertion. Session info: %s", session_info)
        raise PermissionDenied

    auth.login(request, user)
    _set_subject_id(request.session, session_info['name_id'])
    logger.debug("User %s authenticated via SSO.", user)

    logger.debug('Sending the post_authenticated signal')
    post_authenticated.send_robust(sender=user, session_info=session_info)

    # redirect the user to the view where he came from
    default_relay_state = get_custom_setting('ACS_DEFAULT_REDIRECT_URL',
                                             settings.LOGIN_REDIRECT_URL)
    relay_state = request.POST.get('RelayState', default_relay_state)
    if not relay_state:
        logger.warning('The RelayState parameter exists but is empty')
        relay_state = default_relay_state
    if not is_safe_url(url=relay_state, host=request.get_host()):
        relay_state = settings.LOGIN_REDIRECT_URL
    logger.debug('Redirecting to the RelayState: %s', relay_state)
    return HttpResponseRedirect(relay_state)

logger.debug('Trying to authenticate the user. Session info: %s', session_info)
    user = auth.authenticate(request=request,
                             session_info=session_info,
                             attribute_mapping=attribute_mapping,
                             create_unknown_user=create_unknown_user)
    if user is None:
        logger.warning("Could not authenticate user received in SAML Assertion. Session info: %s", session_info)
        raise PermissionDenied

    auth.login(request, user)
    _set_subject_id(request.session, session_info['name_id'])
    logger.debug("User %s authenticated via SSO.", user)

    logger.debug('Sending the post_authenticated signal')
    post_authenticated.send_robust(sender=user, session_info=session_info)

    # redirect the user to the view where he came from
    default_relay_state = get_custom_setting('ACS_DEFAULT_REDIRECT_URL',
                                             settings.LOGIN_REDIRECT_URL)
    relay_state = request.POST.get('RelayState', default_relay_state)
    if not relay_state:
        logger.warning('The RelayState parameter exists but is empty')
        relay_state = default_relay_state
    if not is_safe_url_compat(url=relay_state, allowed_hosts={request.get_host()}):
        relay_state = settings.LOGIN_REDIRECT_URL
    logger.debug('Redirecting to the RelayState: %s', relay_state)
    return HttpResponseRedirect(relay_state)