special">==</span> <span class="identifier">x</span><span class="special">.</span><span class="identifier">base</span><span class="special">()</span></code>
        </p>
<pre class="programlisting"><span class="keyword">void</span> <span class="identifier">advance</span><span class="special">(</span><span class="keyword">typename</span> <span class="identifier">iterator_adaptor</span><span class="special">::</span><span class="identifier">difference_type</span> <span class="identifier">n</span><span class="