ssion<keywords>
  : boost::mpl::true_
{};

default_call_policies some_policies;

void f()
{}

''') -->
<div class="admonition-syntax-note admonition">
<p class="first admonition-title">Syntax Note</p>
<p class="last">A <tt class="docutils literal">(deduced …)</tt> clause always contains a <tt class="docutils literal">(required …)</tt>
and/or an <tt class="docutils literal">(optional …)</tt> subclause, and must follow any
<tt class="docutils literal">(required …)</tt> or <tt class="docutils literal">