In most cases, hash is _consistent_ with =, meaning that for two values x, y,
;; if (= x y), then (= (hash x) (hash y)). This is a property of hash that
;; is relied upon for hash-based lookup of keys in maps and
;; elements in sets to work correctly.
;; There are some pairs of Java objects x, y where even though (= x y) is true,
;; (= (hash x) (hash y)) is _not_ true.
;; Search for the word "consistent" in this article for some categories of such
;; objects:
https://clojure.org/guides/equality;; In particular, the section titled "Equality and hash":
;;
https://clojure.org/guides/equality#equality_and_hash