">decltype</span><span class="special">(</span><span class="identifier">completion</span><span class="special">.</span><span class="identifier">handler</span><span class="special">)&gt;{</span>
        <span class="identifier">completion</span><span class="special">.</span><span class="identifier">handler</span><span class="special">,</span> <span class="special">*</span><span class="keyword">this</span><span class="special">,</span> <span class="identifier">op</span><span class="special">,</span> <span cla