This is used by the algorithm to keep track of the DFS ordering
  of the vertices. The <TT>TimeMap</TT> must be a model
  of <a href="../../property_map/doc/ReadWritePropertyMap.html"> Read/Write
  Property Map</a> and its value type must be an integer type. The key
  type must be the vertex descriptor type of the graph.<br>
  <b>Default:</b>an <a
  href="../../property_map/doc/iterator_property_map.html">
  <tt>iterator_property_map</tt></a> created from a
  <tt>std::vector</tt> of integers with size
  <tt