def save(self, doc):
        if doc.id:
            return self.update(doc)
        else:
            return self.insert(doc)
def test_impl(n):
            S1 = pd.Series(np.ones(n))
            S2 = pd.Series(np.random.ranf(n))
            df = pd.DataFrame({'A': S1, 'B': S2})
            return df.A.sum()