 a match given the matching length, an attribute 
    and the iterator pair pointing to the matching portion of the input</td>
  </tr>
  <td class="table_cells"><b>group_match</b></td>
  <td class="table_cells">For non terminals such as rules, this is called after 
    a successful match has been made to allow post processing</td>
  </tr>
  <td class="table_cells"><b>concat_match</b></td>
  <td class="table_cells">Concatenate two match objects</td>
  </tr>
</table>
<a name="action_policy"></a>
<h2>action_po