an>
  []
  (<span class="mdzsyn-coresym">print</span> <span class="mdzsyn-string">"inside block..."</span>)
  (<span class="mdzsyn-coresym">error</span> <span class="mdzsyn-string">"oops"</span>))

<span class="mdzsyn-comment"># Pass the :e flag to trap errors (and only errors).</span>
<span class="mdzsyn-comment"># All other signals will be propagated up the fiber stack.</span>
(<span class="mdzsyn-coresym">def</span> <span class="mdzsyn-symbol">f</span> (<span class="mdzsyn-coresym">fiber/new</span> <span