def xtest_token_query(self):
     schema = self.schemas['schema1']
     dao = SqlAlchemyDAO(connection=self.connection, schema=schema)
     # Generate data.
     self.connection.execute(
         schema['sources']['substrate'].insert(), 
         [{'id': 'S1', 'label': 's1'}]
     )
     tkn1 = {'ID': 'tkn1', 'EXPRESSION': '__substrate__id'}
     token_registry = {'tkn1': tkn1}
     query_def = {
         'ID': 'test',
         'SELECT': [
             {'ID': 'tkn_id', 'EXPRESSION': '___TOKENS__tkn1'}
         ]
     }
     dao.execute_queries([query_def], token_registry=token_registry)