title: Does this param need to be returned in javascript?
body: <p>I am going through the heads first js book and encountered a problem.</p>
  
  <p>On the Console it comes out as 7 still when it should be 8? This is in the book so I'm guessing I'm just missing something basic here.</p>
  
  <p><div class="snippet" data-lang="js" data-hide="false" data-console="true" data-babel="false">
  <div class="snippet-code">
  <pre class="snippet-code-js lang-js prettyprint-override"><code>var age = 7;
  
  function addOne(x) {
    x = x + 1;
  }
  
  addOne(age);
  console.log(age);</code></pre>
  </div>
  </div>
  </p>