I see it as a positive if a candidate uses an existing solution to the problem. That's exactly what a good engineer would do in the real world. But then I take

I see it as a positive if a candidate uses an existing solution to the problem. That's exactly what a good engineer would do in the real world. But then I take away the library/method and re-state the problem. Because the point is to see if they can understand the problem, and devise a solution.