Movie Groove is an example mashup app, written in Python using Flask. It shows the main concepts of routing, templates, and making external API calls. It is not, however, written in a robust way. Notably, a good app should intelligently handle API errors, timeouts, etc.
The Flask installation guide is quite good. It recommends learning and using virtualenv to create a seperate Python environment for each project -- which is handy.
You can also install Flask (and any other Python package) globally, using the pip package manager. If you're on Python 2.7.9, you already have pip. Then you can do this on the command line:
sudo python -m pip install flask
Otherwise, install pip serparately, and run:
sudo pip install flask
This project also includes a requirements.txt file, so you could:
cd PATH_TO_THIS_PROJECT
sudo pip install -r requirements.txt
Just run movie_groove/app.py! Point your browser to / and /api/docs.