def retrieve(self, request, pk=None):
    if (pk.upper() in self.valid_keys):
        return Response({pk: getattr(config, pk.upper())})
    else:
        raise Http404
def retrieve(self, request, pk=None):
    if (pk.upper() in self.valid_keys):
        return Response({pk: getattr(config, pk.upper())})
    else:
        raise Http404