stra's algorithm.  The type
  <tt>VertexIndexMap</tt> must be a model of
  <a href="../../property_map/ReadablePropertyMap.html">Readable Property Map</a>. The value type of the map must be an
  integer type. The vertex descriptor type of the graph needs to be
  usable as the key type of the map.<br>
  <b>Default:</b> <tt>get(vertex_index, g)</tt>
</blockquote>


UTIL: <tt>distance_map(DistanceMap d_map)</tt> 
<blockquote>
  This parameter is no longer needed, and will be ignored.
</blockquote>

IN: <tt>dis