d>
        <td>&nbsp;
          
        </td>
        <td>
          The container's key type.
        </td>
        <td>
          <tt>Container::value_type</tt>
        </td>
      </tr>
  </table>
    <pre>
    template &lt;<br>          class Container
        , class DerivedPolicies
        , bool NoProxy = false<br>        , bool NoSlice = false
        , class Data = typename Container::value_type
        , class Index = typename Container::size_type
        , class Key = typename Container::value_t