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: ;;;     Title: Graph Formatting
  ;;;   Created: 2002-08-13
  ;;;   License: LGPL (See file COPYING for details).
  ;;;       $Id: graph-formatting.lisp,v 1.12 2005-04-12 20:43:26 ahefner Exp $
  ;;; ---------------------------------------------------------------------------
  
  ;;;  (c) copyright 2002 by Gilbert Baumann
  
negative.code:                                 (let ((v (+ v0 (/ (min 0 d) -2))))
                                    (setf (output-record-position node)
                                          (if (eq orientation :vertical)
                                              (transform-position (medium-transformation stream) v u0)
                                              (transform-position (medium-transformation stream) u0 v)))
                                    (add-output-record node graph-output-record))
                                  ;;
                                  (let ((u (+ u0 (car majors)))
  