To run, first install Flask:

pip install flask

Next, set the following environment variable:

export FLASK_ENV=development

Finally, run flask:

flask run

Visit the URL that is printed in the output to test your app.

To deploy your app, you might consider using Heroku. Once you've created an account, download and install the Heroku CLI. Log in using heroku login.

Next, create a new app on Heroku:

heroku create

Finally, deploy your app:

git push heroku master