anchor.diff:  
   ==== Registration
   
  -[code, ruby]
  +[source, ruby]
   ----
   
     class Converter
  
positive.code: 
  ==== Converter code
  
  [code, ruby]
  ----
  class Converter
  
  
negative.code:  to add the needed behavior to the converter.
  
  
  [source, ruby]
  ----
  
  class Converter
  