> <span class="identifier">Ptree</span> <span class="special">&amp;</span><span class="special">,</span> <span class="keyword">const</span> <span class="identifier">Ptree</span> <span class="special">&amp;</span><span class="special">)</span><span class="special">;</span>
      <span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> Ptree<span class="special">&gt;</span> 
        <span class="keyword">void</span> <a class="link" href="../boost/property_tre