Maybe the question is a bit more general, in the sense of which modules are available in the script, but in this case I need to download the diff_url in a pull request, which I obtain with:

        const diff_url = context.payload.pull_request.diff_url

BTW, specifying the structure of a context.payload object would also be useful

But I don't what I can use to get the contents of that URL into the script. Any idea?