anchor.diff:                                                  (/ (+ x1 x2) 2) from
                                                   (/ (+ u1 u2) 2) to
                                                   arc-drawing-options))))))))
  -                            (map nil continuation children)))))
  +                            (map nil continuation children))))))
   
   (defmethod layout-graph-edges :around ((graph-output-record tree-graph-output-record)
                                          stream arc-drawer arc-drawing-options)
  
positive.code: (defmethod layout-graph-edges ((graph standard-graph-output-record)
                                 stream arc-drawer arc-drawing-options)
    (with-slots (orientation) graph
      (traverse-graph-nodes graph
                            (lambda (node children continuation)
                              (unless (eq node graph)
  
negative.code: ;;;     Title: Graph Formatting
  ;;;   Created: 2002-08-13
  ;;;   License: LGPL (See file COPYING for details).
  ;;;       $Id: graph-formatting.lisp,v 1.13 2005-04-21 03:34:58 ahefner Exp $
  ;;; ---------------------------------------------------------------------------
  
  ;;;  (c) copyright 2002 by Gilbert Baumann
  