pan><span class="special">,</span> <span class="identifier">mpl</span><span class="special">::</span><span class="identifier">false_</span> <span class="keyword">const</span> <span class="special">&amp;</span><span class="special">)</span><span class="special">;</span>
  <span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> T<span class="special">,</span> <span class="keyword">typename</span> U<span class="special">&gt;</span> 
    <span class="keyword">