anchor.diff:  
   [source,clojure]
   ----
  -(cljs.closure/build "src" 
  +(cljs.build.api/build "src" 
     {:output-to "out/main.js"
      :optimizations :advanced})
   ----
  
positive.code: 
  [source,clojure]
  ----
  (cljs.closure/build "src" 
    {:output-to "out/main.js"
     :externs ["yayquery-externs.js"]
     :optimizations :advanced})
  
negative.code: 
  [source,clojure]
  ----
  (cljs.build.api/build "src" 
    {:output-to "out/main.js"
     :optimizations :advanced})
  ----
  