@property
    def _extra_keys(self):
        return []
Unit test of StartCluster() instance status error.
dataset/ETHPy150Open openstack/oslo.db/oslo_db/sqlalchemy/models.py/ModelBase._extra_keys--crossover with--dataset/ETHPy150Open GoogleCloudPlatform/solutions-google-compute-engine-cluster-for-hadoop/gce_cluster_test.py/GceClusterTest.testStartCluster_InstanceStatusError