anchor.diff:  ;;; interface. Run MAIN and press the space bar to start, stop, and
   ;;; clear the timer. Press 'q' to quit.
   
  -;;; Timer state
  +
  +;;; Timer state & manipulation
   
   (defvar *start* nil)
   (defvar *stop* nil)
  
positive.code:                                     printed-time
                                      (- (floor width 2) length/2)
                                      (floor height 2)))))
  
  (defun main ()
    "Start the timer program."
  
negative.code:              *start*)
            internal-time-units-per-second)))
  
  ;;; Rendering function
  
  (defun paint-time ()
    "Paint the elapsed time to the center of the screen."
    (multiple-value-bind (width height)
  