anchor.diff:                                                                    (get-x (x point))
                                                                     (get-y (y point))))
                                                           points))))
  -    (draw scene (:polygon :points string-points :fill "orange" :stroke stroke))))
  +    (if stroke
  +        (draw scene (:polygon :points string-points :fill "orange" :stroke stroke))
  +        (draw scene (:polygon :points string-points :fill "orange")))))
   
   (defun draw-polygons-to-svg (polygons &key (filename "~/polygon.svg"))
  -  (let* ((bounding-box (reduce #'bounding-box-union (mapcar #'cl-geometry::construct-bounding-box polygons)))
  -         (x-min (cl-geometry::x-min bounding-box))
  -         (x-max (cl-geometry::x-max bounding-box))
  -         (y-min (cl-geometry::y-min bounding-box))
  -         (y-max (cl-geometry::y-max bounding-box))
  -         (*x-shift* (if (or (> x-max 1) (< x-min 0))
  -                        (/ (- 1 (+ x-min x-max)) 2)
  -                        0))
  -         (*y-shift* (if (or (> y-max 1) (< y-min 0))
  -                        (/ (- 1 (+ y-min y-max)) 2)
  -                        0))
  -         (max-size (max (- x-max x-min) (- y-max y-min)))
  -         (*border* (if (> max-size 1)
  -                       (+ *border* (round (/ (* *scale* (- max-size 1)) 2)))
  -                       *border*))
  -         (size (+ *scale* (* 2 *border*))))
  +  (with-calculated-size (polygons)
       (with-svg-to-file
           (scene 'svg-1.1-toplevel :height size :width size)
           (filename :if-exists :supersede)
  
positive.code:             (draw group (:line :x1 (+ *scale* (- *border* a3)) :y1 cur-a :x2 (+ *scale* (+ *border* a3)) :y2 cur-a))
              ))))
  
  (defun draw-text (scene text point)
    (text scene (:x (get-x (x point)) :y (get-y (y point))) text))
  
  
negative.code: 
  (defun draw-problem (problem &key (filename "~/field.svg"))
    (let* ((polygons (src/types:silhouette problem))
           (lines (src/types:skeleton problem)))
      (with-calculated-size (polygons)
        (with-svg-to-file
            (scene 'svg-1.1-toplevel :height size :width size)
            (filename :if-exists :supersede)
          (mapc (lambda (polygon) (draw-polygon scene polygon)) polygons)
          (mapc (lambda (line) (draw-line-segment scene line)) lines)
          (draw-field scene)))))
  
  (defun dump-problems (problem-folder)
    (mapc (lambda (problem-file)
  