import tornado.ioloop
import tornado.web


class MainHandler(tornado.web.RequestHandler):
    def get(self):
        self.write("<h1>Hello, world!</h1>")


application = tornado.web.Application([
    (r"/", MainHandler),
])

if __name__ == "__main__":
    application.listen(8888)
    tornado.ioloop.IOLoop.current().start()

add - tornado 版的 hello world.