unction <code>f</code> multiple times on the same element.</p>
<p>Methods on the returned iterable are allowed to omit calling <code>f</code>
on any element where the result isn't needed.
For example, <a href="dart-collection/IterableMixin/elementAt.html">elementAt</a> may call <code>f</code> only once.</p>
    </section>
    
    <section class="summary source-code" id="source">
      <h2><span>Implementation</span></h2>
      <pre class="language-dart"><code class="language-dart">Iterable&lt;T&gt; map&lt;