Fun with Macros: Gathering

I haven’t written anything in a while. But after seeing the metaprogramming video on Computerphile the other day I felt the urge to write about Lisp again, so I decided to do a small series of posts on fun/useful little Common Lisp macros I’ve made over the past couple of years.
The Macro The first macro we’ll look at is gathering:
(defmacro gathering (&body body) "Run `body` to gather some things and return a fresh list of them.