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

        @param requestor: The entity the request originated from.
        @type requestor: L{JID<twisted.words.protocols.jabber.jid.JID>}
        @param service: The entity the request was addressed to.
        @type service: L{JID<twisted.words.protocols.jabber.jid.JID>}
        @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>}
        """
