class="mdzsyn-coresym">when</span> (<span class="mdzsyn-coresym">&gt;</span> <span class="mdzsyn-number">0.05</span> (<span class="mdzsyn-coresym">math/random</span>))
      (<span class="mdzsyn-coresym">print</span> <span class="mdzsyn-string">"worker errored out!"</span>)
      (<span class="mdzsyn-coresym">error</span> <span class="mdzsyn-string">"unexpected error"</span>))
    (<span class="mdzsyn-coresym">++</span> <span class="mdzsyn-symbol">counter</span>))
  (<span class="mdzsyn-coresym">print</span