an class="identifier">node_iter</span><span class="special">::</span><span class="identifier">iterator_adaptor_</span><span class="special">(</span><span class="identifier">other</span><span class="special">.</span><span class="identifier">base</span><span class="special">())</span> <span class="special">{}</span>

 <span class="keyword">private</span><span class="special">:</span>
    <span class="keyword">friend</span> <span class="keyword">class</span> <span class="identifier">boost</span><span class="sp