How to create a workspace to practice Flask basic exercise?

I would like to create an individual workspace to practice Flask-basics. I launched a new workspace with python runtime, however the environment does not contain Flask and if we need to install it, what are the instructions to install it? or my expectation that the launched workspace will have Flask preinstalled correct ?

I am trying to run the following script in the new workspace launched, and am trying to preview I get the following error

Workspace url: https://teamtreehouse.com/workspaces/27820232#

Code to execute/preview:

from flask import Flask from flask import render_template

app = Flask(name)

@app.route('/') def index(): return render_template("index.html")

@app.route('/save', methods=['POST']) def save(): return 'Saved!'

app.run(debug=True, host='0.0.0.0', port=8000)

Use the "eye" icon to preview, it opens up the following url

http://port-8000-gxkoudlulg.treehouse-app.com/

I get the following error:

Workspace Unavailable This is a preview link for a Treehouse Workspace that is not currently active. If you are the workspace owner, you can launch it again via the Treehouse site.