def __repr__(self):
        return "<NamedRequirements({}{})>".format(
            self.name,
            ", filename='{}'".format(self.filename.name) if self.filename
            else "")
def test_impl(n):
            df = pd.DataFrame({'A': ['aa', 'bb', 'aa', 'cc', 'cc']})
            return df.A.nunique()