an class="special">{}</span>

    <span class="keyword">explicit</span> <span class="identifier">PolyRingIterator</span><span class="special">(</span><span class="identifier">I</span> <span class="identifier">ringIter</span><span class="special">)</span> <span class="special">:</span> <span class="identifier">_ringIter</span><span class="special">(</span><span class="identifier">ringIter</span><span class="special">)</span> <span class="special">{}</span>

    <span class="keyword">template</span><span clas