anchor.diff:      
       p It's generally not seen as good practise to polyfill things in node.js. Instead, you're better off just requiring the library wherever you need it.
       
  -    p To install "promise" run:
  -
  -    a.no-link.small-code(href="https://github.com/then/promise")
  +    p To install #[a(href="https://github.com/then/promise") promise] run:
  +
  +    .small-code
         pre: code npm install promise --save
   
       p Then you can load it into a local variable using "require"
   
  -    a.no-link.small-code(href="https://github.com/then/promise")
  +    .small-code
         :js
           var Promise = require('promise');
   
  
positive.code:           Note that #[code promise.done] (used in the examples in
            this section) has not been standardised. It is supported by most
            major promise libraries though, and is usefull both as a teaching
            aid and in production code. I recommend using it along with the following polyfill:
  
          a.no-link.small-code(href="/polyfills/promise-done-1.0.0.js")
            :html
              <script src="http://promisejs.org/polyfills/promise-done-1.0.0.js"></script>
  
      h2#then Transformation / Chaining
  
      p.
  
negative.code:     p.
        Promises are currently only supported by a pretty small selection of browsers
        (#[a(href="http://kangax.github.io/es5-compat-table/es6/#Promise") see kangax compatability tables]).
        The good news is that they're extremely easy to polyfill (#[a(href="/polyfills/promise-" + versions.promise + ".js") link]):
      .small-code(href="/polyfills/promise-" + versions.promise + ".js")
        :html
          <script src="http://promisejs.org/polyfills/promise-#{versions.promise}.js"></script>
      
      p.
        None of the browsers currently support #[code Promise.prototype.done]
        so if you want to use that feature, and you are not including the
        polyfill above, you must at least include this polyfill (#[a(href="/polyfills/promise-done-1.0.0.js") link]):
  
      .small-code
        :html
          <script src="http://promisejs.org/polyfills/promise-done-1.0.0.js"></script>
  
  