(optional …)</tt> clauses indicating
nondeduced parameters at the outer level.</p>
</div>
<p>With the declaration above, the following two calls are equivalent:</p>
<pre class="literal-block">
def(&quot;f&quot;, &amp;f, <strong>some_policies</strong>, <strong>&quot;Documentation for f&quot;</strong>);
def(&quot;f&quot;, &amp;f, <strong>&quot;Documentation for f&quot;</strong>, <strong>some_policies</strong>);
</pre>
<!-- @example.prepend('''
int main()
{''') -->
<p>If the user wants to pass a <tt class="d