             </p>
                </td>
</tr>
<tr>
<td>
                  <p>
                    <code class="computeroutput"><span class="identifier">r</span><span class="special">--</span></code>
                  </p>
                </td>
<td>
                  <p>
                    convertible to <code class="computeroutput"><span class="keyword">const</span> <span class="identifier">X</span><span class="special">&amp;</span></code>
                  </p>
                </td>
<td>
<pre class="progr