I was able to do the first question pretty easily. There were a few things I just forgot about in the moment (regex) that they helpfully provided some guidance on. They were great with this, not patronizing but understanding the stress of a whiteboard session. The second challenge was about creating an interface, which I understand in concept but have never used professionally. I totally failed on this one and sort of knew I was toast after this. Everybody was nice about it but I could see on their faces that it was over.