Why is the text being split by 1000?

[CharlesFr]

I'd like to understand why the text is being split by 1000 characters?

Is it that each chunk if to be submitted using 1000 tokens? (In which case the character limit is 750)

https://github.com/peterw/Chat-with-Github-Repo/blob/918977b440ec41d7dd4451f397e790351a65860b/github.py#L32