title: How do I know when my backfire collection has finished loading from the server?
body: <p>I'm playing with firebase and backfire. The <a href="https://github.com/firebase/backfire" rel="nofollow">example</a> doesn't explicitly say, but I've figured out that it loads data from the server when you instantiate an instance of your <code>Backbone.Firebase.Collection</code>. E.g.:</p>
  
  <pre><code>var TodoList = Backbone.Collection.extend({
    model: Todo,
    firebase: new Backbone.Firebase("https://&lt;your-namespace&gt;.firebaseio.com")
  });
  var todos = new TodoList(); // fetches data
  </code></pre>
  
  <p>How do I know when the retrieval is done?</p>