fier">append</span><span class="special">(</span><span class="identifier">poly</span><span class="special">,</span> <span class="identifier">make_tuple</span><span class="special">(</span><span class="number">0</span><span class="special">,</span> <span class="number">0</span><span class="special">));</span>

    <span class="comment">// Create an interior ring (append does not do this automatically)</span>
    <span class="identifier">boost</span><span class="special">::</span><span class="identifier">geom