  <span class="mdzsyn-string">"E"</span> <span class="mdzsyn-string">"Elephant"</span>})</code></pre><p>As before, we can evaluate this loop using only a <code class="mendoza-code">while</code> loop and the
<code class="mendoza-code">next</code> function. The <code class="mendoza-code">next</code> function is the primary way to iterate in
Janet, and is overloaded to support all iterable types. Given a data structure
and a key, it returns the next key in the data structure. If there are no more
keys left, it