ass="special">}</span>
    <span class="special">};</span>

    <span class="comment">// A function object</span>
    <span class="keyword">struct</span> <span class="identifier">read_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="special">&amp;</span> <span class="identifier">i</span><span class="special">,</span> <span class="identifier">unused_type<