- (do* ((elems (map1 #'car lists) (map1 #'car lists-rest))
- (lists-rest (map1 #'cdr lists) (map1 #'cdr lists-rest)))
- ((dolist (x elems) (when (null x) (return t)))
+ (do* ((tails lists (map1 #'cdr tails))
+ (elems (map1 #'car tails)
+ (map1 #'car tails)))
+ ((dolist (x tails) (when (null x) (return t)))