Angular2 rxjs missing observable.interval method : <p>I'm trying to use the interval method of an observable but I keep getting the error </p>

<pre><code> Property 'interval' does not exist on type 'Observable&lt;any&gt;'.
</code></pre>

<p>I added these imports:</p>

<pre><code>import "rxjs/Rx";
import "rxjs/add/observable/interval";
import "rxjs/observable/IntervalObservable";
</code></pre>
