n class="mdzsyn-symbol">arr</span> <span class="mdzsyn-number">0</span> <span class="mdzsyn-keyword">:hello</span>) <span class="mdzsyn-comment"># -&gt; @[:hello]</span>
(<span class="mdzsyn-coresym">put</span> <span class="mdzsyn-symbol">arr</span> <span class="mdzsyn-number">2</span> <span class="mdzsyn-keyword">:hello</span>) <span class="mdzsyn-comment"># -&gt; @[:hello nil :hello]</span>

(<span class="mdzsyn-coresym">set</span> (<span class="mdzsyn-symbol">arr</span> <span class="mdzsyn-number">0</spa