anchor.diff:                 (draw-tree nnx nny nl ang1 ntrans ndepth)
                  (draw-tree nnx nny nl ang2 ntrans ndepth)))))))
   
  -     (draw-tree (/ width 2) height length -90 1.0 maxdepth))))
  +    (draw-tree (/ width 2) height length -90 1.0 maxdepth))))
   
   
   (defun to-window (x y xmin ymin xmax ymax wxmax wymax)
  
positive.code: (defun increment-pixel (img x y)
    "Increment each color component of the pixel in img at location x,y by 1"
    (if (< (aref img y x 0) 255)
  	  (progn 
  		(incf (aref img y x 0))
  		(incf (aref img y x 1))
  		(incf (aref img y x 2)))))
  
  (defun assign-pixel (img x y iter iterations)
    "Color the pixel of img at location x,y depending on the number of iterations and the max iterations"
  
negative.code: (defun omg-cairo (file-name)
    "Test writing a PNG file with Cairo."
    (let* ((width 800)
           (height 600)
           (cnt 250)
           (tmin 0.0)
           (tmax (* 2.0 pi))
           (dt (/ (- tmax tmin) cnt))
           (xp nil)
           (yp nil))
      (cl-cairo2:with-png-file ((home-dir file-name) :argb32 width height)
                               (cl-cairo2:set-source-rgba 1.0 1.0 1.0 1.0)
                               (cl-cairo2:paint)
                               (cl-cairo2:translate 400.0 300.0)
                               (cl-cairo2:scale 120.0 120.0)
                               (cl-cairo2:set-line-width 0.01)
                               (cl-cairo2:set-source-rgba 0 0 0 1.0)
                               (dotimes (i cnt)
                                 (let* ((tv (* i dt))
                                        (x (* (cos (* 7.0 tv)) (cos tv) 2.0))
                                        (y (* (cos (* 7.0 tv)) (sin tv) 2.0)))
                                   (if (not (and xp yp))
                                       (cl-cairo2:move-to x y)
                                     (cl-cairo2:line-to x y))
                                   (setf xp x)
                                   (setf yp y)))
                               (cl-cairo2:stroke))))
  
  (defun deg-to-rad (deg)
    "Convert degrees to radians."
  