old_contents: # -*- coding: utf-8 -*-
  
  from __future__ import unicode_literals
  
  from . import utils
  from .main import Centerline
  
  __all__ = ['utils', 'Centerline']
  
new_contents: # -*- coding: utf-8 -*-
  
  from __future__ import unicode_literals
  
  from . import utils
  from .main import Centerline
  
  __all__ = ('utils', 'Centerline')
  
subject: Convert the list to a tuple