GoogleCloudPlatform/appengine-guestbook-python — pull request #5 by chadradams (2014-08-18 16:02:26+00:00)
Title: Part2 usingusers

This line is wrong:
application = webapp2.WSGIApplication([('/', MainPage)], debug=True)

It should be:
app = webapp2.WSGIApplication([('/', MainPage)], debug=True)