special">::</span><span class="identifier">use_default</span></code>
          as <code class="computeroutput"><span class="identifier">iterator_adaptor</span></code> 's
          <code class="computeroutput"><span class="identifier">Value</span></code> argument; we could
          have just passed <code class="computeroutput"><span class="identifier">node_iter</span></code>
          's <code class="computeroutput"><span class="identifier">Value</span></code> along to <code class="computeroutput"><span cla