anchor.diff:  ;;; Fall-through Methods For Multiple Objects Drawing Functions
   
   (defmethod medium-draw-points* ((medium basic-medium) coord-seq)
  -  ;; WRONG! 
     (let ((tr (invert-transformation (medium-transformation medium))))
       (with-transformed-positions (tr coord-seq)
  -      (loop for (x y) on coord-seq by #'cddr
  -            do (medium-draw-point* medium x y)))))
  +      (map-repeated-sequence nil 2
  +                             (lambda (x y)
  +                               (medium-draw-point* medium x y))
  +                             coord-seq))))
   
   (defmethod medium-draw-lines* ((medium basic-medium) position-seq)
  -  ;; WRONG! 
     (let ((tr (invert-transformation (medium-transformation medium))))
       (with-transformed-positions (tr position-seq)
  -      (loop for (x1 y1 x2 y2) on position-seq by #'cddddr
  -            do (medium-draw-line* medium x1 y1 x2 y2)))))
  +      (map-repeated-sequence nil 4
  +                             (lambda (x1 y1 x2 y2)
  +                               (medium-draw-line* medium x1 y1 x2 y2))
  +                             position-seq))))
   
   (defmethod medium-draw-rectangles* ((medium basic-medium) coord-seq filled)
  -  ;; WRONG! 
     (let ((tr (invert-transformation (medium-transformation medium))))
       (with-transformed-positions (tr coord-seq)
  -      (loop for (x1 y1 x2 y2) on coord-seq by #'cddddr
  -            do (medium-draw-rectangle* medium x1 y1 x2 y2 filled)))))
  +      (map-repeated-sequence nil 4
  +                             (lambda (x1 y1 x2 y2)
  +                               (medium-draw-rectangle* medium
  +                                                       x1 y1 x2 y2
  +                                                       filled))
  +                             coord-seq))))
   
    
  
positive.code: ;; - Why is (EQ (MAKE-TEXT-STYLE NIL NIL 10) (MAKE-TEXT-STYLE NIL NIL 10.0005)) = T?
  ;;   Does it matter?
  ;; - Don't we want a weak hash-table for *TEXT-STYLE-HASH-TABLE*
  ;; - we need more macro hygiene in WITH-TEXT-STYLE
  ;;
  ;; --GB 2002-02-26
  
  ;;; Media
  
  ;; - MEDIUM-DRAW-POINTS*, MEDIUM-DRAW-LINES*, MEDIUM-DRAW-RECTANGLES*
  ;; - MEDIUM-DRAW-RECTANGLES*: POSITION-SEQ argument can be a
  ;;   vector. Use MAP-REPEATED-SEQUENCE.
  ;;
  ;; --GB 2002-02-26
  
  
negative.code:   (if (and (not (device-font-text-style-p s1))
  	   (not (device-font-text-style-p s2)))
        (let* ((family (or (text-style-family s1) (text-style-family s2)))
               (face1 (text-style-face s1))
               (face2 (text-style-face s2))
               (face (if (subsetp '(:bold :italic) (list face1 face2))
                         '(:bold :italic)
                         (or face1 face2)))
               (size1 (text-style-size s1))
               (size2 (text-style-size s2))
               (size (case size1
  