n class="mdzsyn-identifier">fiber</span><span class="mdzsyn-operator">,</span> <span class="mdzsyn-identifier">Janet</span> <span class="mdzsyn-identifier">err</span><span class="mdzsyn-operator">)</span><span class="mdzsyn-operator">;</span></code></pre><p>Print a janet stacktrace for the given fiber to stderr, or whatever is bound
to the <code class="mendoza-code">:err</code> dynamic binding on the current fiber. You also must supply the
return value or error message raised, as that is not tracked by the 