old_contents: from .session import get_session, AioSession
  
  __all__ = ['get_session', 'AioSession']
  __version__ = '0.5.3a0'
  
new_contents: from .session import get_session, AioSession
  
  __all__ = ['get_session', 'AioSession']
  __version__ = '0.5.3'
  
subject: bump to release version