">::</span><span class="identifier">model</span><span class="special">::</span><span class="identifier">d2</span><span class="special">::</span><span class="identifier">point_xy</span><span class="special">&lt;</span><span class="keyword">double</span><span class="special">&gt;</span> <span class="special">&gt;</span> <span class="identifier">box</span><span class="special">;</span>
    <span class="identifier">box</span> <span class="identifier">b</span> <span class="special">=</span> <span class="identifi