'Cleanup the instance resources .
Instance should have been destroyed from the Hypervisor before calling
this method.
:param context: security context
:param instance: Instance object as returned by DB layer.
:param network_info: instance network information
:param block_device_info: Information about block devices that should
be detached from the instance.
:param destroy_disks: Indicates if disks should be destroyed
:param migrate_data: implementation specific params'

def cleanup(self, context, instance, network_info, block_device_info=None, destroy_disks=True, migrate_data=None, destroy_vifs=True):

    raise NotImplementedError()
