anchor.diff:  	    (location (leaf tree))))
   
   (defmethod prb-save-root ((tree text-file-red-black-tree) root)
  -  (close-storage-stream tree)
  -  (let* ((stream (open-storage-stream tree))
  -	 (header (read-stored-object stream))
  -	 (backup (read-stored-object stream))
  -	 (last-header (last-header tree)))
  -    (unless (and (equality last-header header)
  -
  -		 (equality last-header backup))
  -      (close-storage-stream tree)
  -      (error 'inconsistent-storage)))
     (let ((header (make-storage-header tree))
   	(stream (open-storage-stream tree)))
       (file-position stream :start)
  
positive.code: 
  (defmacro form (number contents)
    `(make-instance 'storage-form 
  		  :number ,number 
  		  :contents ,contents))
  
  (defclass text-file-red-black-object (persistent-red-black-object)
    ((location :initform (make-instance 'storage-location) :initarg :location :accessor location)))
  
negative.code: 	(open (file-name tree) :direction :io :if-exists :overwrite :if-does-not-exist :create :element-type 'character)))
  
  (defun close-storage-stream (tree)
    (finish-output (storage-stream tree))
    (close (storage-stream tree)))
  
  (defmethod prb-open-storage ((tree text-file-red-black-tree))
  