 T<span class="special">,</span> <span class="keyword">typename</span> unique_id<span class="special">,</span> <span class="keyword">bool</span> required <span class="special">=</span> <span class="keyword">false</span><span class="special">&gt;</span> 
<span class="keyword">struct</span> <a class="link" href="typed_keyword.html" title="Struct template typed_keyword">typed_keyword</a> <span class="special">:</span> <span class="keyword">public</span> <span class="identifier">boost</span><span class="special