anchor.diff:              }
   
         section
  -        h1 Generators
  +        h2 Generators
           pre
             code.language-javascript.
               let it = fib();
  
positive.code:             it.next(); // {value: undefined, done: true}
  
        section
          h1 Generators
          pre
            code.language-javascript.
              function *fib() {
  
negative.code:         h3 They also allow 2 way message passing between the generator function and the calling code
  
        section
          h2 Generators
          pre
            code.language-javascript.
              function *gen() {
  