How to define a property based on another property
<p>I want to define a property to some namespace depending on another property. The following is my attempt to assign <code>someNameSpace.x2</code> based on <code>someNameSpace.x1</code>:</p>

<pre><code>someNameSpace = {
  x1: 100,
  x2: x1 * 0.5,
};
</code></pre>

<p>but it fails. What is the correct way to do this?</p>
