I'm following this tutorial

https://developers.google.com/bigquery/docs/authorization#service-accounts-appengine

Here is my main.py code

import httplib2

from apiclient.discovery import build
from google.appengine.ext import webapp
from google.appengine.ext.webapp.util import run_wsgi_app
from oauth2client.appengine import AppAssertionCredentials

# BigQuery API Settings
SCOPE = 'https://www.googleapis.com/auth/bigquery'
PROJECT_NUMBER = 'XXXXXXXXXX' # REPLACE WITH YOUR Project ID

# Create a new API service for interacting with BigQuery
credentials = AppAssertionCredentials(scope=SCOPE)
http = credentials.authorize(httplib2.Http())
bigquery_service = build('bigquery', 'v2', http=http)


class ListDatasets(webapp.RequestHandler):
  def get(self):
    datasets = bigquery_service.datasets()
    listReply = datasets.list(projectId=PROJECT_NUMBER).execute()
    self.response.out.write('Dataset list:')
    self.response.out.write(listReply)


application = webapp.WSGIApplication(
                                     [('/listdatasets(.*)', ListDatasets)],
                                     debug=True)

def main():
  run_wsgi_app(application)

if __name__ == "__main__":
  main()

Here is my app.yaml file code

application: bigquerymashup
version: 1
runtime: python
api_version: 1

handlers:
- url: /favicon\.ico
  static_files: favicon.ico
  upload: favicon\.ico

- url: .*
  script: main.py

And yes i have added app engine service account name in google api console Team tab with can edit permissions. When upload the app and try to access the link it says

Oops! This link appears to be broken.

Ealier i ran this locally and tried to access it using link localhost:8080.Then i thought may be running locally might be giving the error so i uploaded my code to

http://bigquerymashup.appspot.com/

but still its giving error.