an class="p">:</span> <span class="kt">Error</span><span class="p">?)</span> <span class="o">-&gt;</span> <span class="kt">Void</span></code></pre>

                        </div>
                      </div>
                    </section>
                  </div>
                </li>
                <li class="item">
                  <div>
                    <code>
                    <a name="/s:21GetStreamActivityFeed15OpenGraphWorkerC13callbackQueue10completionACSo17OS_dispatch_queueC_y10Foundation3U