intro-declaration"><code class="language-swift">struct EnumeratedSequence&lt;Base : Sequence&gt;</code></div>

<div class="discussion comment">
    <p>An enumeration of the elements of a sequence or collection.</p>

<p><code>EnumeratedSequence</code> is a sequence of pairs (<em>n</em>, <em>x</em>), where <em>n</em>s are
consecutive <code>Int</code> values starting at zero, and <em>x</em>s are the elements of a
base sequence.</p>

<p>To create an instance of <code>EnumeratedSequence</code>, call <code>enumer