anchor.diff:    (setq *transform-spec* spc)
     (setq *transform-specunit-Id* cl-user::*last-unit-Id-_loaded*)
     (setq *transform-term* nil)
  +  (setq *current-qid* nil)
     (setq *transform-commands* nil)
     (setq *undo-stack* nil)
     (setq *prompt* "** ")
  
positive.code: 	()
  	(progn
  	  (push-state `(at-command ,qid))
  	  (setq *transform-term* (PathTerm::toPathTerm new-term))
  	  (push #'(lambda (future-steps)
  		    (if (null future-steps)
  			nil
  
negative.code: (defun push-state (command)
    (unless *redoing?*
      (setq *redos* nil))
    (push (list *transform-term* *transform-commands* *transform-spec* command *current-qid*) *undo-stack*))
  
  (defvar *print-undone-commands* t)
  
  