an class="special">=</span> <span class="identifier">sink</span><span class="special">-&gt;</span><span class="identifier">locked_backend</span><span class="special">();</span>
        <span class="identifier">p</span><span class="special">-&gt;</span><span class="identifier">add_stream</span><span class="special">(</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">make_shared</span><span class="special">&lt;</span> <span class="identifier">std</span><span cl