r">tag</span><span class="special">,</span> <span class="number">0</span><span class="special">);</span>
    <span class="identifier">boost</span><span class="special">::</span><span class="identifier">apply_visitor</span><span class="special">(</span><span class="identifier">walker</span><span class="special">,</span> <span class="identifier">what</span><span class="special">.</span><span class="identifier">value</span><span class="special">);</span>
<span class="special">}</span>
</pre>
<p>
        </p>
<