d">typename</span> <span class="identifier">Collection</span><span class="special">,</span> <span class="keyword">typename</span> <span class="identifier">Strategy</span><span class="special">&gt;</span>
<span class="keyword">void</span> <span class="identifier">sym_difference</span><span class="special">(</span><span class="identifier">Geometry1</span> <span class="keyword">const</span> <span class="special">&amp;</span> <span class="identifier">geometry1</span><span class="special">,</span> <span class="i