</p>
        </section>
                <section class="summary source-code" id="source">
          <h2><span>Implementation</span></h2>
          <pre class="language-dart"><code class="language-dart">Rectangle get first {
  if (this.length &gt; 0) {
    return JS(&#39;Rectangle&#39;, &#39;#[0]&#39;, this);
  }
  throw new StateError(&quot;No elements&quot;);
}</code></pre>
        </section>
</section>
        
        <section id="setter">
        
        <section class="multi-line-signature">
         