old_contents: 
  
  class SequanaException(Exception):
      def __init__(self, *args, **kwargs):
          Exception.__init__(self, *args, **kwargs)
  
  
new_contents: # -*- coding: utf-8 -*-
  #
  #  This file is part of Sequana software
  #
  #  Copyright (c) 2016 - Sequana Development Team
  #
  #  File author(s):
  #      Thomas Cokelaer <thomas.cokelaer@pasteur.fr>
  #
  #  Distributed under the terms of the 3-clause BSD license.
  #  The full license is in the LICENSE file, distributed with this software.
  #
  #  website: https://github.com/sequana/sequana
  #  documentation: http://sequana.readthedocs.io
  #
  ##############################################################################
  
  
  
  class SequanaException(Exception):
      def __init__(self, *args, **kwargs):
          Exception.__init__(self, *args, **kwargs)
  
  
subject: add header