This one is a cheat because read does a lot of the work. I can tolerate treating STDIN&#x2F;OUT as black boxes because they often are. The Scheme interpreter&#x27;s functionality is what&#x27;s custom. The read function is crucial to it. So, it&#x27;s implementation should be included. That puts this way over 7 lines.<p>The good news is that I now know where the name Y Combinator comes from. I imagine it will take me a lot longer to wrap my head around that concept, though. Truly weird haha.