> > Is it a valid defense against copyright infringement to say “we don’t know where we got it, maybe someone else copied it from you first?”
> I mean, in humans it's just referred to as 'experience', 'training', or 'creativity'. Unless your experience is job-only, all the code you write is based on some source you can't attribute combined with your own mental routine of "i've been given this problem and need to emit code to solve it". In fact, you might regularly violate copyright every time you write the same 3 lines of code that solve some common language workaround or problem.
Aren't you moving the goal posts? This is not 3 lines, but instead is 1 to 1 reproducing a complex function that definitely has enough invention height to be copyright able.