anchor.diff:  [source,clojure]
   ----
   (require '[hello-world.core :as hello] :reload)
  -(hello/foo 2 3)
  +(hello/average 20 13)
   ----
   
   You should see the result `5`.
  
positive.code: 
  [source,bash]
  ----
  clj -m cljs.main -c hello-world.core -r
  ----
  
  On Windows:
  
  [source,bash]
  ----
  java -cp "cljs.jar;src" -m cljs.main -c hello-world.core -r
  ----
  
  Your default web browser will open to a page that looks like the following:
  
negative.code: (println "Hello world!")
  
  ;; ADDED
  (defn average [a b]
    (/ (+ a b) 2.0))
  ----
  
  At the REPL prompt, recompile and reload your namespace by evaluating the following:
  