@property
    def is_reserved(self):
        return (self.network_address.is_reserved and
                self.broadcast_address.is_reserved)
AlterField should optimize into CreateModel.
dataset/ETHPy150Open Exa-Networks/exabgp/lib/exabgp/dep/ipaddress.py/_BaseNetwork.is_reserved--crossover with--dataset/ETHPy150Open django/django/tests/migrations/test_optimizer.py/OptimizerTests.test_create_model_alter_field