anchor.diff:    #'(lambda (%gsme)
       (setq *macrop-diversion* #'%%macrop
             *macrocall-diversion* #'%%macrocall
  +          *macroexpand-backquote-diversion* #'%macroexpand-backquote
             *current-macro* nil)
       (%macroexpand %gsme)))
  
positive.code:           %gsme)
        ((eq (car %gsme) 'BACKQUOTE)
            (cons 'BACKQUOTE
                  (%macroexpand-backquote (cdr %gsme))))
        (t  (%macroexpand-call (cons (car %gsme)
                                     (%macroexpand-list (cdr %gsme))))))))
  
  
negative.code: ;;;; Macro expansion
  
  (setq *universe* (cons '*macrop-diversion*
                   (cons '*macroexpand-backquote-diversion*
                   (cons '*macrocall-diversion* *universe*))))
  
  (setq *macrop-diversion* nil
        *macrocall-diversion* nil
        *macroexpand-backquote-diversion* nil
        *current-macro* nil)
  
  ;;;; Expand macros in BACKQUOTE expression.
  ;;;;
  ;;;; This algorithm is incomplete - it doesn't handle
  ;;;; nested backquotes.
  (%set-atom-fun %macroexpand-backquote
    #'(lambda (%gsme)
      (cond
  