old_contents: from mongopool import MongoPool
  
  __all__ = ['mongopool']
  
new_contents: from mongopool import MongoPool
  from pkg_resources import get_distribution, DistributionNotFound
  import os.path
  
  __all__ = ['mongopool']
  
  try:
      _dist = get_distribution('mongopool')
      if not __file__.startswith(os.path.join(_dist.location, 'mongopool')):
          # not installed, but there is another version that *is*
          raise DistributionNotFound
  except DistributionNotFound:
      __version__ = 'Please install this project with setup.py'
  else:
      __version__ = _dist.version
  
subject: Make version accessible from a single place #16