 class="special">&amp;</span><span class="special">)</span><span class="special">;</span>
  <span class="special">}</span><span class="special">;</span>
  <span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> Type<span class="special">&gt;</span> 
  <span class="keyword">struct</span> <a class="link" href="map/on_definedness_Ty_id672484.html" title="Struct template on_definedness&lt;Type, false&gt;">on_definedness</a><span class="special">&lt;</span><spa