">std</span><span class="special">::</span><span class="identifier">basic_ostream</span><span class="special">&lt;</span> <span class="keyword">typename</span> <span class="identifier">Ptree</span><span class="special">::</span><span class="identifier">key_type</span><span class="special">::</span><span class="identifier">value_type</span> <span class="special">&gt;</span> <span class="special">&amp;</span> stream<span class="special">,</span> 
                 <span class="keyword">const</span> <span class