 determine the type
of parameter from the type of the contained class. The type
traits classes provide a transformation &quot;add_reference&quot;,
which adds a reference to its type, unless it is already a
reference.</p>

<table border="1" cellpadding="7" cellspacing="1" width="580">
    <tr>
        <td valign="top" width="21%">Type of &quot;T1&quot;</td>
        <td valign="top" width="27%">Type of &quot;const T1&quot;</td>
        <td valign="top" width="53%">Type of &quot;add_reference&lt;const
        