def search(self, regex):
        try:
            spec = {'$or': [{'data.content'    : {'$regex': regex, '$options': 'im'}},
                            {'data.description': {'$regex': regex, '$options': 'im'}}]}
            fields = {'_id': 0}
            cur = self.db.docs.find(spec, fields)
        except Exception as e:
            raise DatabaseException(e)
        return [Document(**row) for row in cur]
def test_impl(n):
            df = pd.DataFrame({'A': np.arange(n)})
            df['B'] = df.A.map(lambda a: 2 * a)
            return df.B.sum()