an class="special">(</span><span class="identifier">as</span> <span class="special">+</span> <span class="identifier">bs</span><span class="special">)</span> <span class="special">/</span> <span class="number">2</span><span class="special">;</span>
    <span class="special">}</span>
<span class="special">}</span>

<span class="identifier">boost</span><span class="special">::</span><span class="identifier">fibers</span><span class="special">::</span><span class="identifier">fiber</span> <span class="identifi