title: How to smooth stream Rxjs?
body: <p>I have a Rxjs:</p>
  <pre><code>   private loading = new BehaviorSubject(false);
  </code></pre>
  <p>The <code>loading</code> can be changed fast from <code>true</code> to <code>false</code>. How to smooth this stream and pass values only if time between <strong>false</strong> and <strong>true</strong> is more then 3 seconds, otherwise pass false by default?</p>