title: Emberjs: how to iterate over tweets and display date only when different from the last?
body: <p>I'm new to ember, so please forgive if this question has been covered elsewhere.  </p>
  
  <p>Here's a simplified version of the markup I'm trying to get:</p>
  
  <pre><code>&lt;h1&gt;Date1&lt;/h1&gt;
  &lt;div&gt;Tweet 1 on Date1&lt;/div&gt;
  &lt;div&gt;Tweet 2 on Date1&lt;/div&gt;
  &lt;h1&gt;Date2&lt;/h1&gt;
  &lt;div&gt;Tweet 3 on Date2&lt;/div&gt;
  &lt;div&gt;Tweet 4 on Date2&lt;/div&gt;
  </code></pre>
  
  <p>I come from django, so i'm used to the <code>ifchanged</code> tag <a href="https://docs.djangoproject.com/en/dev/ref/templates/builtins/#ifchanged" rel="nofollow">https://docs.djangoproject.com/en/dev/ref/templates/builtins/#ifchanged</a></p>
  
  <p>What's the right way to get this?  I looked into handlebars helpers, but they appear to be stateless.</p>