old_contents: # -*- encoding: utf-8 -*-
  from __future__ import (unicode_literals, absolute_import,
                          division, print_function)
  import json
  
  class OParl(object):
  
      def __init__(self, string):
          self.string = string
          self.data = json.loads(string)
  
      def validate(self):
          raise Exception('Ponies!')
  
new_contents: # -*- encoding: utf-8 -*-
  from __future__ import (unicode_literals, absolute_import,
                          division, print_function)
  import json
  
  class OParlDocument(object):
  
      def __init__(self, string):
          self.string = string
          self.data = json.loads(string)
  
      def validate(self):
          raise Exception('Ponies!')
  
subject: rename class