I ran the following hello world code in python but localhost:8080 doesnot print anything

i'm using ubuntu 12.04

localhost:8080 shows a blank page

helloworld.py

```
import webapp2

class MainPage(webapp2.RequestHandler):

def get(self):
    self.response.headers['Content-Type'] = 'text/plain'
    self.response.write('Hello, World!')

application = webapp2.WSGIApplication([
('/', MainPage),
], debug=True)

```

app.yaml

```
application: your-app-id
version: 1
runtime: python27
api_version: 1
threadsafe: true

handlers:
- url: /.*
  script: helloworld.application

```

output is as follows

```
kiran@kiru-Lenovo-G480:~/google$ dev_appserver.py helloworld/
INFO     2013-10-09 12:22:03,559 sdk_update_checker.py:245] Checking for updates to the SDK.
INFO     2013-10-09 12:22:03,565 __init__.py:94] Connecting through tunnel to: appengine.google.com:443
INFO     2013-10-09 12:22:03,571 sdk_update_checker.py:261] Update check failed: <urlopen error Tunnel connection failed: 407 Proxy Authentication Required>
INFO     2013-10-09 12:22:03,595 api_server.py:138] Starting API server at: http://localhost:44748
INFO     2013-10-09 12:22:03,610 dispatcher.py:168] Starting module "default" running at: http://localhost:8080
INFO     2013-10-09 12:22:03,614 admin_server.py:117] Starting admin server at: http://localhost:8000

```