ostController <span class="token operator">=</span> Ember<span class="token punctuation">.</span>ObjectController<span class="token punctuation">.</span><span class="token function">extend</span><span class="token punctuation">(</span><span class="token punctuation">{</span>
  <span class="token comment">// initial value</span>
  <span class="token literal-property property">isExpanded</span><span class="token operator">:</span> <span class="token boolean">false</span><span class="token punctuation">,</span