/../../doc/src/images/callouts/4.png" alt="4" border="0"></a>
    <span class="identifier">bg</span><span class="special">::</span><span class="identifier">append</span><span class="special">(</span><span class="identifier">mls1</span><span class="special">[</span><span class="number">0</span><span class="special">],</span> <span class="identifier">point_t</span><span class="special">(</span><span class="number">0.0</span><span class="special">,</span> <span class="number">1.0</span><span class="special">))