old_contents: import os
  from collections import namedtuple
  
  
  class DummyRecord(namedtuple('DummyRecord', ('one', 'two', 'three'))):
      """ Dummy record used for testing.
  
      """
  
      @classmethod
      def header(cls):
          return '{0:<5} {1:<5} {2:<5}{newline}'.format(
              *cls._fields, newline=os.linesep)
  
      def line(self):
          return '{0:<5} {1:<5} {2:<5}{newline}'.format(
              *self, newline=os.linesep)
  
new_contents: import os
  from collections import namedtuple
  
  
  class DummyRecord(namedtuple('DummyRecord', ('one', 'two', 'three'))):
      """ Dummy record used for testing.
  
      """
      @classmethod
      def header(cls):
          return u'{0:<5} {1:<5} {2:<5}\n'.format(*cls._fields)
  
      def line(self):
          return u'{0:<5} {1:<5} {2:<5}\n'.format(*self)
  
subject: use the default newline character