docs: def get_volumes_for_instance(self, arg, device=None):
          """
          Return all EC2 Volume objects attached to ``arg`` instance name or ID.
  
          May specify ``device`` to limit to the (single) volume attached as that
          device.
          """
          instance = self.get(arg)
          filters = {'attachment.instance-id': instance.id}
          if device is not None:
              filters['attachment.device'] = device
          return self.get_all_volumes(filters=filters)