n object</span>
    <span class="keyword">struct</span> <span class="identifier">print_action</span>
    <span class="special">{</span>
        <span class="keyword">void</span> <span class="keyword">operator</span><span class="special">()(</span><span class="keyword">int</span> <span class="keyword">const</span><span class="special">&amp;</span> <span class="identifier">i</span><span class="special">,</span> <span class="identifier">qi</span><span class="special">::</span><span class="identifier">unused_ty