><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Iterator</span><span class="special">&gt;</span>
<span class="keyword">class</span> <span class="identifier">filter_iterator</span>
<span class="special">{</span>
 <span class="keyword">public</span><span class="special">:</span>
    <span class="keyword">typedef</span> <span class="identifier">iterator_traits</span><span class="special">&lt;</span><span class="identifier">Iterator</span><span class="special">&gt;::<