anchor.diff:                       :direction :output
                        :if-exists :overwrite
                        :element-type '(unsigned-byte 8))
  -    (when (= (file-position f offset) offset)
  +    (when (file-position f offset)
         (write-sequence token f))))
  
positive.code:                        :direction :output
                         :if-exists :overwrite
                         :element-type '(unsigned-byte 8))
        (when (= (file-position f offset) offset)
          (write-sequence zeroes-buffer f)))))
  
  (defun write-token (path token &optional (offset 0))
  
negative.code:   (with-open-file (f path
                       :direction :input
                       :element-type '(unsigned-byte 8))
      (when (file-position f offset)
        (let ((bytes (make-array *fingerprint-length* :element-type '(unsigned-byte 8))))
          (read-sequence bytes f)
          (every #'= bytes *fingerprint*)))))
  