anchor.diff:            (write-sequence sequence (encapsulated-stream stream)
                             :start start
                             :end end)
  -          (return))))))+          (return))))))
  
positive.code:                    (previous-char previous-char)
                     (external-format external-format)
                     (encapsulated-stream encapsulated-stream)) stream
      (cond
        ;; Newline processing
        ((eql char #\Newline)
         ;; Finish quoting
         (when line-has-non-ascii
           (format encapsulated-stream "?=")
           (setf line-has-non-ascii nil))
         ;; Print CR
         (write-char #\Return encapsulated-stream)
         ;; Test for end of header
  
negative.code:        (loop for byte across (flex:string-to-octets (make-string 1 :initial-element char)
                                                      :external-format external-format)
            do (format encapsulated-stream "=~2,'0X" byte))))
        (unless (eql #\Return char)
          (setf previous-char char))
        (unless (< 127 (char-code char))
  