return {
    problem = {
        {8, 0, 0, 0, 5, 0, 0, 0, 7},
        {0, 6, 1, 0, 0, 0, 0, 0, 0},
        {3, 7, 0, 0, 0, 0, 0, 6, 8},
        {0, 0, 0, 6, 0, 0, 8, 0, 0},
        {0, 1, 0, 0, 9, 0, 0, 2, 0},
        {0, 3, 0, 2, 0, 0, 0, 9, 0},
        {0, 8, 0, 0, 0, 7, 0, 0, 0},
        {0, 0, 0, 0, 0, 0, 4, 0, 1},
        {0, 0, 5, 0, 0, 0, 9, 8, 3},
    }

    solution = {
    }
}