l have an initial capacity of 10.
</p>
<pre class="mendoza-codeblock"><code data-language="janet">(<span class="mdzsyn-coresym">defn</span> <span class="mdzsyn-symbol">worker</span>
  [<span class="mdzsyn-symbol">parent</span>]
  (<span class="mdzsyn-coresym">print</span> <span class="mdzsyn-string">"New thread started!"</span>))

<span class="mdzsyn-comment"># New thread's mailbox has capacity for 32 messages.</span>
(<span class="mdzsyn-coresym">def</span> <span class="mdzsyn-symbol">thread</span> (<span 