@property
    def num_examples(self):
        if self.is_list:
            return len(self.list_or_slice)
        else:
            start, stop, step = self.slice_to_numerical_args(
                self.list_or_slice, self.original_num_examples)
            return stop - start
Message does not require a Contact if a Connection is available.
dataset/ETHPy150Open mila-udem/fuel/fuel/utils/__init__.py/Subset.num_examples--crossover with--dataset/ETHPy150Open rapidsms/rapidsms/rapidsms/contrib/messagelog/tests/test_models.py/MessageLogModelTest.test_no_contact