anchor.diff:  
   ;;; Gray stream default methods.
   
  -
   (defmethod stream-element-type ((stream sys.gray:fundamental-character-stream))
     'character)
   
  
positive.code:   (print-unreadable-object (object stream :type t)
      (format stream "for ~S" (synonym-stream-symbol object))))
  
  (defclass string-output-stream (sys.gray:fundamental-character-output-stream)
    ((element-type :initarg :element-type)
     (string :initarg :string))
    (:default-initargs :string nil))
  
negative.code:   (stream-element-type (shadow-stream-primary stream)))
  
  (defclass string-input-stream (sys.gray:fundamental-character-input-stream
                                 sys.gray:unread-char-mixin
                                 string-stream)
    ((string :initarg :string)
     (start :initarg :start)
     (end :initarg :end)))
  