>(</span><span class="keyword">unsigned</span><span class="special">&amp;</span> <span class="identifier">r_</span><span class="special">)</span> <span class="special">:</span> <span class="identifier">r</span><span class="special">(</span><span class="identifier">r_</span><span class="special">)</span> <span class="special">{}</span>
    <span class="keyword">unsigned</span><span class="special">&amp;</span> <span class="identifier">r</span><span class="special">;</span>
<span class="special">};</span>
</p