(defn do-blowfish [directive]
  (case directive
    :aquarium/blowfish (println "feed the fish")
    :crypto/blowfish   (println "encode the message")
    :blowfish          (println "not sure what to do")))

(ns crypto)
(user/do-blowfish:blowfish)
; not sure what to do

(user/do-blowfish::blowfish)
; encode the message

(ns aquarium)
(user/do-blowfish:blowfish)
; not sure what to do

(user/do-blowfish::blowfish)
; feed the fish