title: How do I get the last value from a ReplaySubject?
body: <p>Below is a snippet that describes what I'm trying to do.  In my application I have a replaysubject that's used throughout.  At a certain point I want to get the last value emitted from the subject, but <code>last</code> doesn't seem to work on a ReplaySubject.</p>
  
  <pre><code>const subject = new Rx.ReplaySubject();
  
  subject.next(1);
  subject.next(2);
  subject.next(3);
  subject.next(4);
  
  subject.subscribe(num =&gt; console.log(num));
  
  var lastObserver = subject.last();
  lastObserver.subscribe(num =&gt; console.log('last: ' + num));
  </code></pre>
  
  <p><a href="https://jsfiddle.net/b05r434a/5/" rel="noreferrer">FIDDLE</a></p>
  
  <p>The code above doesn't fire anything for the <code>lastObserver</code>, but subscribe works just fine.</p>