_:outerlist . _:outerlist _:lista . _:outerlist _:b0 . _:lista "a1" . _:lista _:a2 . _:a2 "a2" . _:a2 _:a3 . _:a3 "a3" . _:a3 . _:c0 _:c1 . _:c0 . _:c1 "c1" . _:c1 _:c2 . _:c2 "c2" . _:c2 _:c3 . _:c3 "c3" . _:c3 . _:b0 _:b1 . _:b0 _:c0 . _:b1 "b1" . _:b1 _:b2 . _:b2 "b2" . _:b2 _:b3 . _:b3 "b3" . _:b3 .