ecause the return value of the slot will be
            cached.</p>
<p>The <code class="computeroutput">const</code> version of
            the function call operator will invoke the combiner as
            <code class="computeroutput">const</code>, whereas the
            non-<code class="computeroutput">const</code> version will
            invoke the combiner as
            non-<code class="computeroutput">const</code>.</p>
</td>
</tr>
</tbody>
</table></div>
</li></ol></div>
</div>
<div class="refsect2"