Hello world tornado app

hello_world.py

+import tornado.ioloop
+import tornado.web
+
+
+class MainHandler(tornado.web.RequestHandler):
+    def get(self):
+        self.write("Hello, world")
+
+
+def make_app():
+    return tornado.web.Application([
+        (r"/", MainHandler),
+    ])
+
+if __name__ == "__main__":
+    app = make_app()
+    app.listen(80)
+    tornado.ioloop.IOLoop.current().start()