anchor.diff:    (let ((rack (make-array 2 :initial-contents '(10 1))))
       (make-s :class nil :rack rack)))
   
  -(defun y (instance)
  +(defun y1 (instance)
     (declare (optimize (safety 0) (speed 3) (debug 0)))
     (let* ((rack (s-rack instance))
            (stamp (svref rack 0)))
  
positive.code:         (svref rack 1)
          (error "1"))))
  
  (proclaim '(notinline y))
  
  (defun g ()
    (declare (optimize (safety 0) (speed 3) (debug 0)))
    (loop with j = *j*
          repeat 1000000000
  	do (y j)))
  
  (time (g)) ; < 3s
  
  (defun yy (instance)
    (declare (optimize (safety 0) (speed 3) (debug 0)))
    (let* ((rack (s-rack instance))
           (stamp (svref rack 0)))
  
negative.code:            (error "8"))
            (t (svref rack 1)))))
  
  (proclaim '(notinline y3))
  
  (defun g3 ()
    (declare (optimize (safety 0) (speed 3) (debug 0)))
    (loop with j = *j*
          repeat 1000000000
          do (y3 j)))
  
  (time (g3)) ; < 4.5s
  
  (defun y4 (instance)
    (declare (optimize (safety 0) (speed 3) (debug 0)))
    (let* ((rack (s-rack instance))
           (stamp (svref rack 0)))
      (declare (type fixnum stamp))
      (if (< stamp 2)
          (if (< stamp 1)
              (svref rack 1)
              (svref rack 2))
          (if (< stamp 3)
              (svref rack 3)
              (svref rack 4)))))
  
  (proclaim '(notinline y4))
  
  (defun make (stamp)
    (let ((rack (make-array 5
                            :initial-contents
                            (cons stamp '(1 1 1 1)))))
      (make-s :class nil :rack rack)))
  
  (defun g4 ()
    (declare (optimize (safety 0) (speed 3) (debug 0)))
    (loop with j0 = (make 0)
          with j1 = (make 1)
          with j2 = (make 2)
          with j3 = (make 3)
          repeat 250000000
          do (y4 j0) (y4 j2) (y4 j1) (y4 j3)))
  
  (time (g4)) ; 3.3s
  