new_contents: def app(env, start_response):
      start_response('200 OK', [('Content-Type','text/html')])
      return [b"Hello World"]
  
  if __name__ == '__main__':
      try:
          from wsgiref.simple_server import make_server
          httpd = make_server('', 8080, app)
          print('Serving on port 8080...')
          httpd.serve_forever()
      except KeyboardInterrupt:
          print('Goodbye.')
  
subject: Return 'Hello World' by wsgiref