Andrej Karpathy says he used some code autocomplete while rewriting a tokenizer in Rust, relying on a Python implementation he fully understood to create a more efficient version and add tests.

“So I was doing there's a bit of byte coding going on in when I was writing some of the Rust code.”

“But I had Python implementation that I fully understand and I'm just making sure I'm making more efficient version of it and add tests.”