anchor.diff:  
   (defconstant* %integer-instance-classes%
     (let ((c (compute-end-classes (find-class 'integer))))
  -    #+CCL (cons '(find-clas fixnum) c)
  +    #+CCL (cons (find-class 'fixnum) c)
       #-CCL c))
   
   (defconstant* %float-instance-classes%
  
positive.code: ;; (= (/ pi 4) (@atan 2d0 2d0))
  ;; => T
  
  ;; also
  ;; (= (rationalize (/ pi 4d0)) (rationalize (@atan 2d0 2d0)))
  ;;
  ;; although
  ;; (= (/ (rationalize pi) 4) (rationalize (@atan 2d0 2d0)))
  
negative.code: ;; (= (/ (rational pi) 4) (rational (@atan 2d0 2d0)))
  ;; => T
  ;;
  
  ;;
  ;; thus illustrating some of the contrasting qualities of CL:RATIONAL 
  ;; and CL:RATIONALIZE - onto that simple wrapper for diadic ATAN
  