@abstractmethod
    def unregister(self, fileobj):
        raise NotImplementedError
Exercising select_related() with multi-table model inheritance.
dataset/ETHPy150Open dpkp/kafka-python/kafka/selectors34.py/BaseSelector.unregister--crossover with--dataset/ETHPy150Open django/django/tests/select_related_regress/tests.py/SelectRelatedRegressTests.test_multi_table_inheritance