anchor.diff:  				(or (find-common-window code-point next-code-point)
   				    (codepoint-to-window-offset code-point))
   				write-func +SD0+ +SDX+)
  -	  (encode-unit* state code-point next-code-point write-func lookahead-func))
  +	  (encode-unit* state code-point next-code-point write-func))
   	 ((or (standalone-character-p code-point)
   	      ;; not both suitable for unicode-mode => next char can be encoded smally (1byte).
   	      (encoded-1byte-p state next-code-point)
  
positive.code: (deftype write-func-type ()
    '(function ((unsigned-byte 8)) t))
  
  (deftype lookahead-func-type ()
    '(function (fixnum) t))
  
  (defun in-window-p (offset code-point)
    (declare (type unicode-code-point offset code-point))
    (<= offset code-point (+ offset #x7f)))
  
negative.code: 		    (t			; change
  		     (scsu-change-to-window state dwindow)
  		     (funcall write-func (+ +SC0+ dwindow))
  		     (encode-unit* state code-point next-code-point write-func))))))
  	 ;; 3byte or more
  	 ;; TODO: add test code for this part.
  	 ((use-define-window-p state code-point) ; define window
  