anchor.diff:        li Documents behavior
         li Binds to test cases
   
  -  section(data-narration="/bdd/8")
  +  section(data-narration="/bdd/9")
       h2 Example: Gherkin
       pre.
         Feature: App store validates customer credit card
  
positive.code:       li Gherkin
        li Behave
        li Features and steps
        li Mocha
negative.code:   section(data-narration="/bdd/7")
      h2 But what is a consistent format?
  
    section(data-narration="/bdd/8")
      h2 One Format: Gherkin
      ul
        li Domain specific language
  