anchor.diff:    (alexandria:when-let (fn (variable-value 'find-definitions-function :buffer))
       (funcall fn (current-point))))
   
  -(defun show-references (refs)
  +(defun display-xref-references (refs)
     (unless refs
       (editor-error "No references found"))
     (push-location-stack (current-point))
  
positive.code:    :xref-filespec-to-filename
     :move-to-xref-location-position
     :indent-size
     :display-xref-locations)
    #+sbcl
    (:lock t))
  (in-package :lem.language-mode)
  
negative.code: (define-command find-references () ()
    (alexandria:when-let (fn (variable-value 'find-references-function :buffer))
      (let ((refs (funcall fn (current-point))))
        (display-xref-references refs))))
  
  (defvar *xref-stack-table* (make-hash-table :test 'equal))
  (defvar *xref-history-table* (make-hash-table :test 'equal))
  