anchor.diff:  
   So, let's tell it to compare an `is` with a `should` and log the result. 
   
  -[code,javascript]
  +[source,javascript]
   ----
   function test(is, should) {
     console.log (is === should);
  
positive.code: 
  My version looks like this:
  
  [code,javascript]
  ----
  function test(is, should, msg) {
    if (is === should) {
  
negative.code: 
  First, review our error message.
  
  [source,bash]
  ----
  /*
  Exception: ReferenceError: test is not defined
  