title: Unsubscribe from events in observableCollection
body: <p>Lets say I have an observableCollection of classes:</p>
  
  <pre><code>CustomClassName testClass = new CustomClassName();
  ObservableCollection&lt;CustomClassName&gt; collection = new ObservableCollection&lt;CustomClassName&gt;();
  testClass.SomeEvent += OnSomeEvent;
  collection.add(testClass);
  </code></pre>
  
  <p>When I will remove items from a collection, do i need manually unsubscribe from events(OnSomeEvent) or should I leave it for a GC? 
  And what is the best way to unsubscribe?</p>