anchor.diff:       ,@(mapcar #'((x)
    	                (if (consp x)
   		     		    x
  -		     			(aif (assoc x *tagbody-replacements*)
  +		     			(aif (cdr (assoc x *tagbody-replacements*))
   		       				!
   		       				x)))
                  args)
  
positive.code:                       ,@(if (vm-jump? (car tail))
  						    tail
  						    `((%setq ~%ret ,@tail)))))
               (bname (assoc block-name *blockname-replacements*)))
          (if bname
              (nconc ret (list bname) '((identity ~%ret)))
              (nconc ret '((identity ~%ret)))))
  
negative.code: ;;; is expanded.
  
  (define-compiler-macro go (label)
    (aif (cdr (assoc label *tagbody-replacements*))
      `(vm-go ,!)
      (with-gensym g
        (acons! label g *tagbody-replacements*)
  