anchor.diff:  
   (defstruct xref-location
     (filespec nil :read-only t :type (or buffer string pathname))
  -  (position 1 :read-only t :type integer)
  +  (position 1 :read-only t)
     (title "" :read-only t :type string))
   
   (defstruct xref-references
  
positive.code:       (unless locations
          (editor-error "No definitions found"))
        (push-location-stack (current-point))
        (if (null (rest locations))
            (go-to-location (first locations))
            (let ((prev-file nil))
  
negative.code:     (if pop-to-buffer
          (setf (current-window) (pop-to-buffer buffer))
          (switch-to-buffer buffer))
      (let ((position (xref-location-position location)))
        (etypecase position
          (integer
           (move-to-position (current-point) position))
          (cons
           (move-to-line (current-point) (car position))
           (line-offset (current-point) 0 (cdr position)))
          (point
           (let ((line-number (line-number-at-point position))
                 (charpos (point-charpos position)))
             (move-to-line (current-point) line-number)
             (line-offset (current-point) 0 charpos)))))))
  
  (define-command find-definitions () ()
    (alexandria:when-let (fn (variable-value 'find-definitions-function :buffer))
  