def get_docs_to_commit(self):
        try:
            spec = {'synced': False}
            fields = {'_id': 0}
            cur = self.db.docs.find(spec, fields)
        except Exception as e:
            raise DatabaseException(e)
        return list(cur)
def test_impl(df):
            A = df.A.str.split(',')
            B = pd.Series(list(itertools.chain(*A)))
            return B