def METHOD_NAME(self, serializer):
    inst = serializer.save(organizer=self.request.organizer)
    inst.log_action(
        'pretix.reusable_medium.created',
        user=self.request.user,
        auth=self.request.auth,
        data=merge_dicts(self.request.data, {'id': inst.pk})
    )
    mt = MEDIA_TYPES.get(serializer.validated_data["type"])
    if mt:
        m = mt.handle_new(self.request.organizer, inst, self.request.user, self.request.auth)
        if m:
            s = self.get_serializer(m)
            return Response({"result": s.data})