his default, make sure your graph has
    an internal <tt>vertex_index</tt> property. For example,
    <tt>adjacency_list</tt> with <tt>VertexList=listS</tt> does
    not have an internal <tt>vertex_index</tt> property.
   <br>
</blockquote>

OUT: <tt>OutputIterator o</tt>
<blockquote>
  The OutputIterator holds the vertices of the tour.
  The type <tt>OutputIterator</tt> must be a model of the
  OutputIterator concept.
</blockquote>

OUT: <tt>TSPTourVisitor vis</tt>
<blockquote>
  Use this to specify actio