What's the best open source Contract Bridge software?

Excellent open source ML sparing partners for Chess and Go are available: https://github.com/bencaddigan/esports-for-engineers

But what about Contract Bridge? Is there an open source program that will play the other three hands? A machine learning program would be ideal, but any decent open source program would be fine.

It would be interesting to see what bidding conventions a machine learning algorithm would create.