(defun intersect (x y)
	(do	((first x  (cdr first))
		 (result NIL (if (member (car first) y) 
		 		 (cons (car first) result)
				 result)))
		((null first) result)))

(defun union (x y)
	(do	((first x  (cdr first))
		 (result y (if (member (car first) y)
		 		result
				(cons (car first) result))))
		((null first) result)))