* (cartprod2 '(a b c) '(1 2 3 4))
((A . 1) (A . 2) (A . 3) (A . 4)
 (B . 1) (B . 2) (B . 3) (B . 4)
 (C . 1) (C . 2) (C . 3) (C . 4))