# Learn Classes and Objects by Building a Sudoku Solver - Step 44

``````class Board:
def __init__(self, board):
self.board = board

def __str__(self):
upper_lines = f'\n╔═══{"╤═══"*2}{"╦═══"}{"╤═══"*2}{"╦═══"}{"╤═══"*2}╗\n'
middle_lines = f'╟───{"┼───"*2}{"╫───"}{"┼───"*2}{"╫───"}{"┼───"*2}╢\n'
lower_lines = f'╚═══{"╧═══"*2}{"╩═══"}{"╧═══"*2}{"╩═══"}{"╧═══"*2}╝\n'
board_string = upper_lines
for index, line in enumerate(self.board):
row_list = []
for square_no, part in enumerate([line[:3], line[3:6], line[6:]], start=1):
row_square = '|'.join(str(item) for item in part)
row_list.extend(row_square)
if square_no != 3:
row_list.append('║')

row = f'║ {" ".join(row_list)} ║\n'
row_empty = row.replace('0', ' ')
board_string += row_empty

if index < 8:
if index % 3 == 2:
board_string += f'╠═══{"╪═══"*2}{"╬═══"}{"╪═══"*2}{"╬═══"}{"╪═══"*2}╣\n'
else:
board_string += middle_lines
else:
board_string += lower_lines

return board_string

def find_empty_cell(self):
for row, contents in enumerate(self.board):
try:
col = contents.index(0)
return row, col
except ValueError:
pass
return None

def valid_in_row(self, row, num):
return num not in self.board[row]

def valid_in_col(self, col, num):
return all(
self.board[row][col] != num
for row in range(9)
)

# User Editable Region

def valid_in_square(self, row, col, num):

# User Editable Region

``````

User Agent is: `Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/121.0.0.0 Safari/537.36 Edg/121.0.0.0`

### Challenge Information:

Learn Classes and Objects by Building a Sudoku Solver - Step 44

How have you created other functions in the past? Is there something you put on the second line?

I put pass on the second line but it still didn’t work

Hi @carrie1

Your code passes, just ass `pass` keyword in the body and make sure the indentation is correct.