anchor.diff:  
   (defun yen (stream object &optional colon-p at-sign-p digits-after-dot
   	    &aux (style (flag-to-style colon-p at-sign-p)))
  -  (unless (realp object)
  -    (error "~A is not an expected type for yen" (type-of object)))
  +  (check-type object real "jp-numeral:yen acceptable type")
     (unless digits-after-dot
       (setf digits-after-dot 2))
     (multiple-value-bind (signum yen sen rin)
  
positive.code:    (stringify-float object digits-after-dot scale)
     style radix-point-string))
  
  
  (defun make-digits4-string (digits4 style base-power)
    (declare (type (integer 0 9999) digits4))
  
negative.code:        (write-string (get-power power style) stream))))
  
  
  ;; entry point
  (defun format-jp-numeral (stream object style
  			  &key digits-after-dot scale radix-point)
    (check-type object number "jp-numeral acceptable type")
    (prog ((*print-base* 10)    ; *print-base* must be 10 for jp-numeral
  	 (scale (or scale 0))
  	 (radix-point-str (etypecase radix-point
  