25         using L3 = mp_list<void, void>;  in main()  typedef
29         BOOST_TEST_TRAIT_TRUE((std::is_same<mp_flatten<L3>, L3>));  in main()
33         BOOST_TEST_TRAIT_TRUE((std::is_same<mp_flatten<L3, L3>, L3>));  in main()
35         using L4 = mp_transform<mp_list, L3>;  in main()
37         BOOST_TEST_TRAIT_TRUE((std::is_same<mp_flatten<L4>, L3>));  in main()
38         BOOST_TEST_TRAIT_TRUE((std::is_same<mp_flatten<L4, mp_list<>>, L3>));  in main()
41         using L5 = mp_transform<std::tuple, L3>;  in main()
45         BOOST_TEST_TRAIT_TRUE((std::is_same<mp_flatten<L5, std::tuple<>>, L3>));  in main()
51         using L3 = std::tuple<void, void>;  in main()  typedef
55         BOOST_TEST_TRAIT_TRUE((std::is_same<mp_flatten<L3>, L3>));  in main()
59         BOOST_TEST_TRAIT_TRUE((std::is_same<mp_flatten<L3, L3>, L3>));  in main()
61         using L4 = mp_transform<mp_list, L3>;  in main()
64         BOOST_TEST_TRAIT_TRUE((std::is_same<mp_flatten<L4, mp_list<>>, L3>));  in main()
67         using L5 = mp_transform<std::tuple, L3>;  in main()
69         BOOST_TEST_TRAIT_TRUE((std::is_same<mp_flatten<L5>, L3>));  in main()
71         BOOST_TEST_TRAIT_TRUE((std::is_same<mp_flatten<L5, std::tuple<>>, L3>));  in main()