ModuleNotFoundError: No module named 'fcntl' [duplicate]
It has already been mentioned in https://stackoverflow.com/a/11087777/12362709 (thanks to @Necklondon) but copying it here since it's useful:
pip install waitresswaitress-serve --listen=*:8000 app:app
If you'd like to run gunicorn on windows, this is possible using the Ubuntu terminal available for windows: https://ubuntu.com/tutorials/ubuntu-on-windows#1-overview
The terminal will allow linux commands to work. I use it to run gunicorn myself.