code: public void setVertexOrder(List<String> vertex_list)
  	{
  	    if (!vertex_list.containsAll(getGraph().getVertices())) 
  	        throw new IllegalArgumentException("Supplied list must include " +
  	        		"all vertices of the graph");
  	    this.vertex_ordered_list = vertex_list;
  	}
docs: Sets the order of the vertices in the layout according to the ordering
  of {@code vertex_list}.