lass="special">;</span>

  <span class="comment">// <a class="link" href="version.html#idp40412928-bb">public member functions</a></span>
  <span class="identifier">argument_type</span> <a class="link" href="version.html#idp40413488-bb"><span class="keyword">operator</span><span class="special">(</span><span class="special">)</span></a><span class="special">(</span><span class="keyword">const</span> <span class="identifier">argument_type</span> <span class="special">&amp;</span><span class="special">)</span