       s.parentNode.insertBefore(ga, s)
       return
 
+    ###
+    Update a custom vars
+    ###
     setVar: (slot, key, value, level=kls.PAGE_LEVEL) ->
       win._gaq.push ['_setCustomVar', slot, key, value, level]
       this

      this.domain = null

    ###
    Whether GA script is loaded
    ###
    isInitialized: -> typeof win._gat isnt "undefined"

    ###
    Inject Google Analytics tracking script
    ###
    initialize: ->
      return if this.isInitialized()

      domain: "kopi.com"
    tracker.load()
    tracker.pageview("/xs/46/")
    tracker.event("book", "download", "1")
  ###
  class Tracker

