mple</h3>
<pre class="language-dart"><code>Observable.range(4, 1)
  .concatMap((i) =&gt;
    new Observable.timer(i, new Duration(minutes: i))
  .listen(print); // prints 4, 3, 2, 1
</code></pre>
    </section>
    
    <section class="summary source-code" id="source">
      <h2><span>Implementation</span></h2>
      <pre class="language-dart"><code class="language-dart">Observable&lt;S&gt; concatMap&lt;S&gt;(Stream&lt;S&gt; mapper(T value)) =&gt;
    Observable&lt;S&gt;(_stream.asyncExpand(mapper));</code>