eyword">static</span> <span class="keyword">const</span> <span class="keyword">int</span> <span class="identifier">arity</span> = <span class="identifier">N</span><span class="special">;</span>  <span class="comment">// The number of arguments taken by the signal.</span>

  <span class="comment">// member classes/structs/unions</span>
  <span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">unsigned</span> n<span class="special">&gt;</span> 
  <span class="keyword">class