anchor.diff:  
   (defvar *transform-spec*)
   (defvar *transform-specunit-Id*)
  -(defvar *transform-term*)		; Actually a pair of current term and its parent
  +(defvar *transform-term*)		; Actually a pair of root and path to current term
  +(defvar *current-qid*)
   (defvar *transform-commands*)
   (defvar *undo-stack*)
   (defvar *redos*)
  
positive.code:   (setq *transform-spec* spc)
    (setq *transform-specunit-Id* cl-user::*last-unit-Id-_loaded*)
    (setq *transform-term* nil)
    (setq *transform-commands* nil)
    (setq *undo-stack* nil)
    (setq *prompt* "** ")
  
negative.code: 	()
  	(progn
  	  (push-state `(at-command ,qid))
  	  (setq *transform-term* (PathTerm::typedPathTerm new-term))
            (setq *current-qid* qid)
  	  (push #'(lambda (future-steps)
  		    (if (null future-steps)
  			nil
  