anchor.diff:                          (format t "  :write     Write a variable by id (from :vars) to the current frame.~%")
                           (format t "  :bt        Print a complete backtrace.~%")
                           (format t "  :condition Condition that caused the debugger to be invoked.~%")
  +                        (format t "  :terminate Terminate the current thread.~%")
                           (format t "Integers are treated at restart IDs.~%")
                           (format t "Good luck.~%"))
                          (:restarts
  
positive.code:                             (dolist (v result)
                                (fresh-line)
                                (write v)))))
                         (t (format t "Unknown command ~S~%" form))))
                      (t (let ((result (multiple-value-list (let ((- form))
                                                              (eval form)))))
  
negative.code: 
  (defun show-restarts (restarts)
    (let ((restart-count (length restarts)))
      (format t "Available restarts:~%")
      (loop
         for i from 0
         for restart in restarts
         do (format t "~S ~S: ~A~%" (- restart-count i 1) (restart-name restart) restart))))
  
  (defun map-backtrace (fn)
    (do ((i 0 (1+ i))
  