@ksaj
To some extent you could write them more similarly. I believe the return is implied in both. the age = is just a verbose style. The cond would use :otherwise or the python would use elif years >= 2. Obviously, lisp has rationals.
I guess my one is a bit different: I viewed it as lazily indexing into an infinite series of dog ages. I suffer a bit from needing to make number atoms into series. And the numbers-everywhere feels messy, though I guess I write messily (cAsE)
@loke @praetor