anchor.diff:        each iteration into an array. Sometimes functions end with loops that are
         intended to run only for their side-effects. Be careful that you're not
         accidentally returning the results of the comprehension in these cases,
  -      by adding a meaningful return value, like <tt>true</tt>, or <tt>null</tt>,
  +      by adding a meaningful return value &mdash; like <tt>true</tt> &mdash; or <tt>null</tt>,
         to the bottom of your function.
       </p>
       <p>
  
positive.code:       to CoffeeScript functions, they nonetheless return their final value.
        The CoffeeScript compiler tries to make sure that all statements in the
        language can be used as expressions. Watch how the <tt>return</tt> gets
        pushed down into each possible branch of execution, in the function
        below.
      </p>
      <%= code_for('expressions', 'eldest') %>
  
negative.code:       <b class="header">Function binding</b>
        In JavaScript, the <tt>this</tt> keyword is dynamically scoped to mean the
        object that the current function is attached to. If you pass a function as
        a callback, or attach it to a different object, the original value of <tt>this</tt>
        will be lost. If you're not familiar with this behavior,
        <a href="http://www.digital-web.com/articles/scope_in_javascript/">this Digital Web article</a>
        gives a good overview of the quirks.
  