def get_version(self):
        raise NotImplementedError
Expect a formula card to require variables.
dataset/ETHPy150Open openstack/python-opentsdbclient/opentsdbclient/base.py/BaseOpenTSDBClient.get_version--crossover with--dataset/ETHPy150Open heiskr/sagefy/server/test/test_models_cards_formula_card.py/test_formula_variables