def delete(self, doc):
        if doc.id is None:
            raise DatabaseException('Document does not have id')
        if doc.sid is None:
            try:
                rs = self.db.docs.remove({'id': doc.id}, safe=True)
                assert rs['n'] == 1
            except Exception as e:
                raise DatabaseException(e)
            return None
        doc.data = None
        return self.update(doc)
def test_impl():
            A = StringArray(['ABC', 'BB', 'ADEF'])
            df = pd.DataFrame({'A': A})
            B = df.A.str.contains('AB*', regex=True)
            return B.sum()