old_contents: class BaseDataFormat(object):
      """Base data format class."""
  
      def get_type(self):
          raise NotImplementedError
  
      def encode(self, data):
          raise NotImplementedError
  
      def decode(self, data):
          raise NotImplementedError
  
new_contents: class BaseDataFormat(object):
      """Base data format class."""
  
      def __init__(self, **options):
          pass
  
      def get_type(self):
          raise NotImplementedError
  
      def encode(self, data):
          raise NotImplementedError
  
      def decode(self, data):
          raise NotImplementedError
  
subject: Add default constructor