an><span class="Other">;</span> <span class="Identifier">listener</span><span class="Other">:</span> <span class="Keyword">proc</span> <span class="Other">(</span><span class="Identifier">message</span><span class="Other">:</span> <span class="Identifier">T</span><span class="Other">)</span><span class="Other">:</span> <span class="Identifier">void</span><span class="Other">)</span></pre></dt>
<dd>

Add a proc to handle events.  Proc will be called once for each event emit.  See the <tt class="docutils lite