erence_type</span> <span class="identifier">distance_to</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">PolyRingIterator</span><span class="special">&amp;</span> <span class="identifier">other</span><span class="special">)</span> <span class="keyword">const</span>
    <span class="special">{</span>
        <span class="keyword">return</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">distance</span><span class="s