s="special">(</span>
    <span class="identifier">implementation_type</span> <span class="special">&amp;</span> <span class="identifier">impl</span><span class="special">,</span>
    <span class="keyword">bool</span> <span class="identifier">mode</span><span class="special">,</span>
    <span class="identifier">boost</span><span class="special">::</span><span class="identifier">system</span><span class="special">::</span><span class="identifier">error_code</span> <span class="special">&amp;</span> <span cla