Oh wow it is precisely the problem I "predicted" before: there are surprisingly few production grade implementations to plagiarize from.
Even for seemingly simple stuff. You might think parsing floating point numbers from strings would have a gazillion examples. But it is quite tricky to do it correctly (a correct implementation allows you to convert a floating point number to a string with enough digits, and back, and always obtain precisely the same number that you started with). So even for such omnipresent example, which has probably been implemented well over 10 000 times by various students, if you start pestering your bot with requests to make it better, if you have the bots write the tests and pass them, you could end up plagiarizing something identifiable.
edit: and even suppose there were 2, or 3, or 5 exfat implementations. They would be too different to "blur" together. The deniable plagiarism that they are trying to sell - "it learns the answer in general from many implementations, then writes original code" - is bullshit.
