Now you should be able to execute the file with python and see a server on your local machine:
$ python shortly.py * Running on http://127.0.0.1:5000/ * Restarting with reloader: stat() polling
It also tells you that the reloader is active. It will use various techniques to figure out if any file changed on the disk and then automatically restart.
Just go to the URL and you should see “Hello World!”.