def shared_lock(self):
        return self.lock(False)
It's an abstract function V21APIExtensionBase and the extension
dataset/ETHPy150Open sdispater/orator/orator/query/builder.py/QueryBuilder.shared_lock--crossover with--dataset/ETHPy150Open BU-NU-CLOUD-SP16/Trusted-Platform-Module-nova/nova/api/openstack/compute/baremetal_nodes.py/BareMetalNodes.get_controller_extensions