title: Rx : Force observable to take at least N seconds to complete
body: <p>I am making a splash screen for my app. I want it to last at least N seconds before going to the main screen. </p>
  
  <p>I have an <strong>Rx</strong> variable <code>myObservable</code> that returns data from the server or from my local cache. How do I force <code>myObservable</code> to complete in <strong>at least N seconds</strong>?</p>
  
  <pre><code>myObservable
  // .doStuff to make it last at least N seconds
     .subscribe(...)
  </code></pre>