title: How to unsubscribe/stop Observable?
body: <p>I use the following code for timer:</p>
  
  <pre><code>export class TimerService {
    private ticks: number = 0;
    private seconds: number = 0;
    private timer;
  
    constructor(seconds: number) {
      this.seconds = seconds;
      this.timer = Observable.timer(2000, 1000);
      this.timer.subscribe(t =&gt; {
        this.ticks = t;
        this.disactivate();
      });
    }
  
    private disactivate() {
      if (this.ticks === this.seconds) {
        this.timer.dispose();
      }
    }
  }
  </code></pre>
  
  <p>When I try to stop timer in line:</p>
  
  <pre><code>this.timer.dispose(); // this.timer.unsubscribe();
  </code></pre>
  
  <p>It does not work for me</p>