implement solve_row0_tile(...)
test solve_row0_tile(...)
clean up solve_row1_tile(...)
clean up solve_row0_tile(...)
clean up solve_interior_tile(...)
clean up solve_col0_tile(...)
make separate test scripts for solve_col0_tile(...)
clean up solve_row1_tile(...)
clean up solve_interior_tile(...)
split up tests into different suites