title: Property 'filter' does not exist on type 'Observable<Event>'
body: <p>Hi I am using Angular 2 final with router 3.0. I want to filter the events that are emitted from <code>this.router.events</code></p>
  
  <p>What I want to do : </p>
  
  <pre class="lang-js prettyprint-override"><code>import 'rxjs/operator/filter';
  
  //...
  
  this.router.events
    .filter((event:Event) =&gt; event instanceof NavigationEnd)
    .subscribe(x =&gt; console.log(x))
  </code></pre>
  
  <p><code>event</code> can be instanceOf <code>NavigationEnd</code>, <code>NavigationStart</code> or <code>RoutesRecognized</code> but I want only <code>NavigationEnd</code>. But I get an error that </p>
  
  <p><code>Property 'filter' does not exist on type Observable&lt;Event&gt;</code></p>
  
  <p>during compile time.</p>
  
  <p>When i import the whole <code>rxjs</code> library the error disappears. What should I import to make it work without loading the full rxjs library ?</p>