def test_type(self):
        rset = event.ResultSet()
        with pytest.raises(NotImplementedError):
            rset.extend([])
        with pytest.raises(NotImplementedError):
            rset.extend(False)
def sort(cls, dataset, by=[], reverse=False):
        cols = [dataset.get_dimension(d, strict=True).name for d in by]
        return dataset.data.sort_values(by=cols, ascending=not reverse)