anchor.diff:      h1 Create private variables
       p
         | The revealing module pattern (
  -      em 'num'
  +      em 'num' 
         | is private):
       pre.
         var number = (function(){
  
positive.code:   .content
      h1 IIFEs in the wild: jQuery Plugins
      p
        | Seal your code in a new scope, alias the global
        em jQuery
        | function as
        em $
        | :
      pre.
  
negative.code:     h1 Why pass 'i' to the for-loop IIFE?
      p
        | Javascript has lexical (function) scope, so
        em i 
        | is shared by all functions created in this loop.
      p
        | The IIFE locks in
        em i 
        | 's value, otherwise we get this:
      pre.
          for (var i = 1; i <= 3; i++) {  
  