I'm no lisp hacker, so that part stood out to me as particularly hard to understand in comparison to the rest of the code which was perfectly clear to me. I had

I'm no lisp hacker, so that part stood out to me as particularly hard to understand in comparison to the rest of the code which was perfectly clear to me. I had to re-read it a number of times to figure out what it meant; obviously, if I was at all familiar with lisp I would have had no trouble with it.