    operation
                </p>
              </th>
<th>
                <p>
                  type
                </p>
              </th>
<th>
                <p>
                  semantics, pre/post-conditions
                </p>
              </th>
</tr></thead>
<tbody>
<tr>
<td>
                <p>
                  <code class="computeroutput">a.get_executor()</code>
                </p>
              </td>
<td>
                <p>
                  A type satisfying the <a class="link" href="Ex