Type</span><span class="p">?)</span> <span class="o">-&gt;</span> <span class="kt">Void</span><span class="p">)?</span> <span class="o">=</span> <span class="kc">nil</span><span class="p">,</span>
            <span class="nv">onSubscribe</span><span class="p">:</span> <span class="p">((</span><span class="kt"><a href="../Protocols/SubscriptionType.html">SubscriptionType</a></span><span class="p">)</span> <span class="o">-&gt;</span> <span class="kt">Void</span><span class="p">)?</span> <span class="o">=</sp