title: Reactive Observable Subscription Disposal
body: <p>If I have access to an IObservable that I know is only ever going to return one item, will this work and is it the best usage pattern?</p>
  
  <pre><code>IDisposable disposable = null;
  disposable = myObservable.Subscribe(x =&gt;
    {
       DoThingWithItem(x);
       if (disposable != null)
       {
         disposable.Dispose();
       }
    });
  </code></pre>