(import (scheme base) (picrin control list) (picrin test)) (test '(1 2 3) (for (yield (in '(1 2 3))))) (test '((1 a) (1 b) (1 c) (2 a) (2 b) (2 c) (3 a) (3 b) (3 c)) (for (let ((n (in '(1 2 3))) (c (in '(a b c)))) (yield (list n c)))))