Given examples, Copilot can generate code for extremely rare languages or data structures. For example, it worked fine when I was writing for an obscure scripting language found in a railway simulation game.
to further elaborate, Copilot automatically grabs most recent 20 files with same extension to get code examples. you dont have to do anything special to make this happen. it just improves quietly over time.
I think he means he uses an obscure programming language and co-pilot still gives him functioning code if he gives a few examples. Not sure if copilot is very context aware where you can feed it an entire code-base, but maybe you can point GPT to read the documentation
That sounds really interesting and valuable, I just have no idea where to start.