title: Binding true / false to radio buttons in Knockout JS
body: <p>In my view model I have a IsMale value that has the value true or false.</p>
  
  <p>In my UI I wish to bind it to the following radio buttons:</p>
  
  <pre><code>&lt;label&gt;Male
     &lt;input type="radio" name="IsMale" value="true" data-bind="checked:IsMale"/&gt;
  &lt;/label&gt; 
  &lt;label&gt;Female
     &lt;input type="radio" name="IsMale" value="false" data-bind="checked:IsMale"/&gt;
  &lt;/label&gt;
  </code></pre>
  
  <p>The problem I think is <code>checked</code> expects a string "true" / "false". So my question is, how can I get this 2-way binding w/ this UI and model?</p>