 class="docutils literal">graph</tt> parameter, we use an asterix to indicate that
any type is allowed.  Required parameters must always precede any
optional parameters in a signature, but if there are <em>no</em>
required parameters, the <tt class="docutils literal">(required … )</tt> clause can be omitted
entirely.</p>
</div>
<!-- @example.prepend('''
#include <boost/parameter.hpp>

BOOST_PARAMETER_NAME(graph)

BOOST_PARAMETER_FUNCTION((void), f, tag,
''') -->
<!-- @example.append(') {}') -->
<!-- @test