title: Is the first() operator will do the unsubscribe automatically?
body: <p>I want to unsubscribe the observable, shall i use the first() operator for unsubscribe?</p>
  
  <p>Example below,</p>
  
  <pre><code>Rx.Observable.interval(100)
  .do(x =&gt; console.log(x))
  .first()
  .subscribe(x =&gt; x);
  </code></pre>
  
  <p>Is the above code will do automatic unsubscribe or need to do anything?</p>