launch_demo_ui.sh : got python ImportError: No module named ext.session

[ngondard]

Not sure whether it's due to python versions on my setup. When I launched the launch_demo_ui.sh script, I got the following error:
python ImportError: No module named ext.session

In the straw_app.py file, I replaced the 4rth line with this one (cf. https://stackoverflow.com/questions/51313324/modulenotfounderror-no-module-named-flask-session):
from flask_session.\_\_init__ import Session

I was then able to launch the UI.