def affiliations(request):
    """
        Called when a affiliations retrieval request has been received.

        @param request: The publish-subscribe request.
        @type request: L{wokkel.pubsub.PubSubRequest}
        @return: A deferred that fires with a C{list} of affiliations as
            C{tuple}s of (node identifier as C{unicode}, affiliation state as
            C{str}). The affiliation can be C{'owner'}, C{'publisher'}, or
            C{'outcast'}.
        @rtype: L{Deferred<twisted.internet.defer.Deferred>}
        """
