':return: A sequence of two attached volumes\' ``blockdevice_id``.'

def attached_volumes(self):

    dataset1 = uuid4()
    dataset2 = uuid4()
    this_node = self.cache.compute_instance_id()
    attached_volume1 = self.cache.attach_volume(self.cache.create_volume(dataset_id=dataset1, size=LOOPBACK_MINIMUM_ALLOCATABLE_SIZE).blockdevice_id, attach_to=this_node)
    attached_volume2 = self.cache.attach_volume(self.cache.create_volume(dataset_id=dataset2, size=LOOPBACK_MINIMUM_ALLOCATABLE_SIZE).blockdevice_id, attach_to=this_node)
    return (attached_volume1.blockdevice_id, attached_volume2.blockdevice_id)
