Flask (Python) server that allows non-blocking execution AFTER response returns. It's hacky but it works (unlike asyncio 😡).
brew install python3
pip3 install Flask
FLASK_APP=server.py /Library/Frameworks/Python.framework/Versions/3.6/bin/flask run
Browse to http://localhost:5000/
You will see messages printed in this order:
received request
blocking
responding
non-blocking with args ['foo' '123']
Note: includes both blocking and non-blocking code.