istance_result</span><span class="special">&lt;</span> <span class="keyword">typename</span> <span class="identifier">point_type</span><span class="special">&lt;</span><span class="identifier">Geometry1</span><span class="special">&gt;::</span><span class="identifier">type</span><span class="special">,</span> <span class="keyword">typename</span> <span class="identifier">point_type</span><span class="special">&lt;</span><span class="identifier">Geometry2</span><span class="special">&gt;::</span><span class=