Clojurians Log v2

@juhoteperi Yes, i wrote that initially. I just looked at Appendix #2, but can't see that it is saying anything particularly wrong. I guess these days there are some other things like :<> to mention? I must be forgetting something. As I remember, it is there primarily because, early on, when we were young and foolish, we tried to pass a vector literal in as a prop ... and it took a very long time to figure out the error message :-)