https://clojuredocs.org/clojure.core.logic/membero Membero FYI

https://stackoverflow.com/a/16371536/2609980an implementation:

(defne nonmembero
  "A relation where l is a collection, such that l does not contain x"
  [x l]
  ([_ ()])
  ([_ [head . tail]]
     (!= x head)
     (nonmembero x tail)))

Thanks!