pan class="mdzsyn-coresym">def</span> <span class="mdzsyn-symbol">file</span> (<span class="mdzsyn-coresym">file/open</span> <span class="mdzsyn-string">"myfile.txt"</span> <span class="mdzsyn-keyword">:w</span>))
(<span class="mdzsyn-coresym">defn</span> <span class="mdzsyn-symbol">worker</span>
  [<span class="mdzsyn-symbol">parent</span>]
  (<span class="mdzsyn-coresym">with-dyns</span> [<span class="mdzsyn-keyword">:out</span> <span class="mdzsyn-symbol">file</span>]
    (<span class="mdzsyn-coresym">pr