 &lt;&lt; root_vertex &lt;&lt; std::endl;
   std::cout &lt;&lt; &quot;index_map=&quot; &lt;&lt; index_map &lt;&lt; std::endl;
   std::cout &lt;&lt; &quot;color_map=&quot; &lt;&lt; color_map &lt;&lt; std::endl;
}

int main()
{
    depth_first_search(1, 2, 3, 4, 5);

    depth_first_search(
        &quot;1&quot;, '2', _color_map = '5',
        _index_map = &quot;4&quot;, _root_vertex = &quot;3&quot;);
}
</pre>
<p class="compound-last">Despite the fact that default expressions such as
<tt class="docutils liter