(LETREC SUMFOLD
	(SUMFOLD LAMBDA (Z) (FOLDRIGHT ADDTHEM (QUOTE 1) Z))
	(ADDTHEM LAMBDA (X Y) (ADD X Y))
	(FOLDRIGHT LAMBDA (FUN B XS)
		(IF (EQ XS (QUOTE NIL)) B
			(FUN (CAR XS) (FOLDRIGHT FUN B (CDR XS))))))&