://www.boost.org/libs/python/doc/v2/callbacks.html#argument_handling">
      <code>ptr</code></a>, <a href=
      "http://www.boost.org/libs/python/doc/v2/callbacks.html#argument_handling">
      <code>ref</code></a>, or <a href="CallPolicies.html">Call Policies</a>
      such as <code><a href=
      "return_internal_reference.html">return_internal_reference</a></code>.
      More details <a href="#HeldType">below</a>.</td>

      <td><code>T</code></td>
    </tr>

    <tr>
      <td><code><font color="#007