def simple_app(environ, start_response):
    status = '200 OK'
    response_headers = [('Content-type','text/plain')]
    start_response(status, response_headers)
    return ['Hello world!\n']

if __name__ == '__main__':
    from wsgiref import simple_server
    httpd = simple_server.make_server('', 8080, simple_app)
    try:
        httpd.serve_forever()
    except KeyboardInterrupt:
        pass