Comment by zahlman

My understanding is: the training induces it to put Python code inside Markdown code fences, which the app interprets. It does that because the training data is full of examples of people doing that, because when people post Python code online it's very commonly in contexts where Markdown is understood that way.

... I suppose they could train the LLM to put a Markdown horizontal rule in the right place, but it sounds harder to get the system prompt to care about details like that consistently.