_</span><span class="special">(</span><span class="number">0</span><span class="special">)</span> <span class="special">{}</span>

    <span class="keyword">explicit</span> <span class="identifier">node_iter</span><span class="special">(</span><span class="identifier">Value</span><span class="special">*</span> <span class="identifier">p</span><span class="special">)</span>
      <span class="special">:</span> <span class="identifier">node_iter</span><span class="special">::</span><span class="identifier">it