an class="keyword">typename</span> <a class="link" href="../../Expr.html" title="Concept Expr">Expr</a><span class="special">,</span> <span class="keyword">typename</span> State<span class="special">,</span> <span class="keyword">typename</span> Data<span class="special">&gt;</span> 
  <span class="keyword">struct</span> <a class="link" href="logical_not/impl.html" title="Struct template impl">impl</a> <span class="special">:</span>
    <span class="keyword"></span> <a class="link" href="pass_through.html" 