ap
its name in <tt class="docutils literal"><span class="pre">in_out(…)</span></tt>:</p>
<pre class="compound-last literal-block">
(optional
    (visitor,            *, boost::dfs_visitor&lt;&gt;())
    (root_vertex,        *, *vertices(graph).first)
    (index_map,          *, get(boost::vertex_index,graph))
    (<strong>in_out(color_map)</strong>, *,
      default_color_map(num_vertices(graph), index_map) )
)
</pre>
</div>
<!-- @example.prepend('''
#include <boost/parameter.hpp>

namespace boost
{
  int