title: Ember how to call computed property with arguements
body: <pre><code>checked: ((key, value) -&gt;
          selected = @get 'controllers.a.selected'
          a = @get 'model'
          if arguments.length &gt; 1
            if value
              selected.addObject a
            else
              selected.removeObject a
  
          return selected.contains a
        ).property('controllers.a.selected.length')
  </code></pre>
  
  <p>Now I am trying to call the checked property.
  I tried to use <code>@controller.get('checked')</code>,
  but how do I pass <code>key, value</code> arguments so that I can test the property. 
  I do not know how to call it. Thanks a lot. </p>