an class="special">(</span><span class="keyword">const</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">string</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="keyword">int</span> <span class="special">=</span> <span class="number">0</span><span class="special">,</span> 
                 