anchor.diff:  
   [source,clojure]
   ----
  -(ns hello-world.core
  -  (:require [clojure.browser.repl :as repl]))
  -
  -(defonce conn
  -  (repl/connect "http://localhost:9000/repl"))
  +(ns hello-world.core)
   
   (enable-console-print!)
   
  
positive.code: ----
  
  The first time will be somewhat slow as the REPL communication script
  needs to build. You will also see innocuous `WARNING`s from the Google
  Closure Compiler that can be ignored. You should eventually see the
  following message:
  
  [source,bash]
  ----
  
negative.code: specify `:output-dir` so that the REPL can reuse compiled files
  generated by the build.
  
  Let's try it:
  
  [source,clojure]
  