pan> <span class="special">{</span>

        <span class="identifier">iterator</span><span class="special">()</span> <span class="special">:</span> <span class="identifier">a</span><span class="special">(</span><span class="number">1</span><span class="special">),</span> <span class="identifier">b</span><span class="special">(</span><span class="number">1</span><span class="special">)</span> <span class="special">{}</span>

        <span class="keyword">int</span> <span class="keyword">operator</span><span 