>!self.isEmpty</code>, remove the first element and return it, otherwise
return <code>nil</code>.</p>

<p><strong>Complexity:</strong> O(<code>self.count</code>)</p>

    <h4>Declaration</h4>    
    <code class="language-swift">mutating func popFirst() -&gt; Self.Generator.Element?</code>
    
        <h4>Declared In</h4>
        <a href="../../protocol/CollectionType/"><code>CollectionType</code></a>    
</div></div>
</div>
<div class="declaration inherited" id="func-subsequence-self-poplast">
<a class="t