old_contents: from ._version import __version__
  from .dockerspawner import DockerSpawner
  from .systemuserspawner import SystemUserSpawner
  
new_contents: from ._version import __version__
  from .dockerspawner import DockerSpawner
  from .systemuserspawner import SystemUserSpawner
  
  __all__ = ['__version__', 'DockerSpawner', 'SystemUserSpawner']
  
subject: declare __all__ in __init__