38     using boost::fusion::at_c;  in main()
66         BOOST_TEST((!at_c<0>(attr)));  in main()
67         BOOST_TEST((at_c<1>(attr).get() == 'a'));  in main()
69         at_c<1>(attr) = optional<char>(); // clear the optional  in main()
71         BOOST_TEST((at_c<0>(attr).get() == 123));  in main()
72         BOOST_TEST((!at_c<1>(attr)));  in main()
74         at_c<0>(attr) = optional<int>(); // clear the optional  in main()
76         BOOST_TEST((at_c<0>(attr).get() == 123));  in main()
77         BOOST_TEST((at_c<1>(attr).get() == 'a'));  in main()
79         at_c<0>(attr) = optional<int>(); // clear the optional  in main()
80         at_c<1>(attr) = optional<char>(); // clear the optional  in main()
82         BOOST_TEST((at_c<0>(attr).get() == 123));  in main()
83         BOOST_TEST((at_c<1>(attr).get() == 'a'));  in main()
107         BOOST_TEST((!at_c<0>(attr)));  in main()
108         BOOST_TEST((at_c<1>(attr).get() == 'a'));  in main()
110         at_c<1>(attr) = optional<char>(); // clear the optional  in main()
112         BOOST_TEST((at_c<0>(attr).get() == 123));  in main()
113         BOOST_TEST((!at_c<1>(attr)));  in main()
115         at_c<0>(attr) = optional<int>(); // clear the optional  in main()
117         BOOST_TEST((at_c<0>(attr).get() == 123));  in main()
118         BOOST_TEST((at_c<1>(attr).get() == 'a'));  in main()
120         at_c<0>(attr) = optional<int>(); // clear the optional  in main()
121         at_c<1>(attr) = optional<char>(); // clear the optional  in main()
123         BOOST_TEST((at_c<0>(attr).get() == 123));  in main()
124         BOOST_TEST((at_c<1>(attr).get() == 'a'));  in main()