def _get_kwargs(self, category, tag):
        """Helper function for getting category/tag kwargs."""
        vals = {
            'categories__title__iexact': category,
            'tags__name__iexact': tag
        }
        kwargs = {}
        for k, v in vals.items():
            if v:
                kwargs[k] = v
        return kwargs
Helper function for getting category/tag kwargs.