code: def _make_subvolume(self, **args):
          
  
          from imagemounter.volume import Volume
          v = Volume(disk=self.disk, parent=self.parent,
                     volume_detector=self.volume_detector,
                     **args)  # vstype is not passed down, let it decide for itself.
          self.volumes.append(v)
          return v
docs: Creates a subvolume, adds it to this class and returns it.