pan></a><span class="special">;</span>

  <span class="comment">// <a class="link" href="impl.html#id-1_3_34_5_49_2_1_1_5_4-bb">public member functions</a></span>
  <span class="identifier">result_type</span> <a class="link" href="impl.html#id-1_3_34_5_49_2_1_1_5_4_1-bb"><span class="keyword">operator</span><span class="special">(</span><span class="special">)</span></a><span class="special">(</span><span class="keyword">typename</span> <span class="identifier">impl</span><span class="special">::</span><spa