Websockets example! In this case a two-player game where participants click on grid points and 
they light up on the other participant's grid.

To get started:
- install recent Python (I think 3.6+ will do it)
- pip install websockets
- run the server in the terminal / command line:
python game_server.py
- load http://localhost:8000 in a web browser
- load http://localhost:8000 again in a *different* web browser

If needed IT support should be able to help with proxying this on the server, so that the
experiment code can use a web link without a different port (and possibly use HTTPS if that's
required).
