old_contents: 
  try:
      from .mzn.aio import *
  except SyntaxError as err:
      raise ImportError(
          'You need Python 3.6 or higher to use the pymzn.aio package.'
      ) from err
  
  
new_contents: 
  try:
      from .mzn import aio as _aio
      from .mzn.aio import *
      __all__ = _aio.__all__
  except SyntaxError as err:
      raise ImportError(
          'You need Python 3.6 or higher to use the pymzn.aio package.'
      ) from err
  
  
subject: add __all__