If you really want though, you can write a web server in a single python lambda:

    (lambda flask:
        (lambda app:
            (app,
            app.route('/')(
                lambda: 'Hello World!'
            )
            )[0]
        )(flask.Flask('__name__')).run()
    )(__import__('flask'))

See https://gist.github.com/e000/1023982 for more horrible examples