class="nv">indices</span> <span class="nv">that</span> <span class="nv">correspond</span> <span class="nv">to</span> <span class="nv">duplicate</span> <span class="nv">entries</span>.

<span class="k">For</span> <span class="nv">performance</span> <span class="nv">reasons</span>, <span class="nv">the</span> <span class="nv">first</span> <span class="nv">two</span> <span class="nv">passes</span> <span class="nv">are</span> <span class="nv">taken</span> <span class="nv">out</span> <span class="nv">of</span> <