anchor.diff:        (fresh-line)
         (backtrace 15)
         (fresh-line)
  -      (write-line "Enter a restart number or evaluate a form.")
  +      (write-line "Enter a restart number or evaluate a form. :help for help.")
         (loop
            (let ((* nil) (** nil) (*** nil)
                  (/ nil) (// nil) (/// nil)
  
positive.code:                             (format t "At outermost frame!~%")
                              (setf *current-debug-frame* (nth (1- (first *current-debug-frame*)) frames)))
                          (show-debug-frame))
                         (:current (show-debug-frame))
                         (:vars
                          (show-debug-frame)
                          (debugger-show-variables *current-debug-frame*))
  
negative.code: (defvar *current-debug-frame* nil)
  
  (defun function-from-frame (frame)
    (let* ((return-address (memref-signed-byte-64 (second frame) 1))
           (fn-address (base-address-of-internal-pointer return-address))
           (fn-offset (- return-address fn-address)))
      (%%assemble-value fn-address +tag-object+)))
  
  (defun read-frame-slot (frame slot)
    (memref-t (memref-unsigned-byte-64 (second frame) 0) (- (1+ slot))))
  
  (defun write-frame-slot (frame slot value)
    (setf (memref-t (memref-unsigned-byte-64 (second frame) 0) (- (1+ slot)))
          value))
  
  (defun show-debug-frame ()
  