uces an optional value.</p>

<p><strong><code>transform</code>:</strong>  A closure that accepts an element of this sequence
  as its argument and returns an optional value.</p>

<p><strong>Complexity:</strong> O(1)</p>

    <h4>Declaration</h4>    
    <code class="language-swift">func flatMap&lt;ElementOfResult&gt;(_ transform: @escaping (LazyFilterSequence&lt;Base&gt;.Elements.Iterator.Element) -&gt; ElementOfResult?) -&gt; LazyMapSequence&lt;LazyFilterSequence&lt;LazyMapSequence&lt;LazyFilterSequence&lt