def whyNot(self):
        return _CantReachThroughGlassBox()
``detach_volume`` raises ``UnattachedVolume`` if the supplied
dataset/ETHPy150Open twisted/imaginary/ExampleGame/examplegame/glass.py/_ObstructedByGlass.whyNot--crossover with--dataset/ETHPy150Open ClusterHQ/flocker/flocker/node/agents/testtools/_blockdevice.py/IBlockDeviceAPITestsMixin.test_detach_detached_volume