Flask-gae-template is a project mainly written in PYTHON and SHELL, it's free.
Template of Google App Engine with Flask.
$ git clone http://github.com/jugyo/flask-gae-template.git app
$ cd app
$ ./setup.sh
dev_appserver.py .
and open 'http://localhost:8080/'.
You should fix application name of app.yaml before deploy.
appcfg.py update .
http://flask.pocoo.org/