anchor.diff:      (gl:clear :color-buffer :depth-buffer))
   
     (sdl2:with-init (:everything)
  -    (sdl2:with-window (win :w 1280 :h 720 :flags '(:shown :opengl))
  +    (sdl2:with-window (win :w +width+ :h +height+ :flags '(:shown :opengl))
         (sdl2:with-gl-context (gl-context win)
           (sdl2:gl-make-current win gl-context)
           (init)
  
positive.code: 
    (defun init ()
      (gl:enable :depth-test)
      (gl:viewport 0 0 1280 720)
      (gl:matrix-mode :projection)
      (gl:ortho -2 2 -2 2 -2 2)
      (gl:matrix-mode :modelview)
  
negative.code: ;(in-package #:cl-foo)
  
  (require :sdl2)
  
  (defconstant +width+ 1280)
  (defconstant +height+ 720)
  
  (defun main-loop ()
    (defun keydown-actions (scancode)
  