        The implementation of <code class="computeroutput"><span class="identifier">node_iter</span></code>
          is thus reduced to:
        </p>
<pre class="programlisting"><span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">Value</span><span class="special">&gt;</span>
<span class="keyword">class</span> <span class="identifier">node_iter</span>
  <span class="special">:</span> <span class="keyword">public</span> <span clas