LY_ASSERT_SMOB (Book, book_smob, 1);
LY_ASSERT_SMOB (Output_def, default_paper, 2);
LY_ASSERT_SMOB (Output_def, default_layout, 3);
LY_ASSERT_SMOB (Book, book_smob, 1);
LY_ASSERT_SMOB (Output_def, default_paper, 2);
LY_ASSERT_SMOB (Output_def, default_layout, 3);