def __repr__(self):
        return "<Requirement(package={package}, version='{version}')>".format(
            package=self.package, version=self.version)
def index(self, request):
        queryset = Condition.objects.select_related('source', 'target_option')
        serializer = ConditionIndexSerializer(queryset, many=True)
        return Response(serializer.data)