### Tell us what’s happening:

Shouldn’t the instruction say “If the recursive call returns None” instead of “False”? I couldn’t get the False to come up, but when I used print(gameboard.solver()), it gave me None

### Your code so far

```
class Board:
def __init__(self, board):
self.board = board
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))
def valid_in_square(self, row, col, num):
row_start = (row // 3) * 3
col_start = (col // 3) * 3
for row_no in range(row_start, row_start + 3):
for col_no in range(col_start, col_start + 3):
if self.board[row_no][col_no] == num:
return False
return True
def is_valid(self, empty, num):
row, col = empty
valid_in_row = self.valid_in_row(row, num)
valid_in_col = self.valid_in_col(col, num)
valid_in_square = self.valid_in_square(row, col, num)
return all([valid_in_row, valid_in_col, valid_in_square])
# User Editable Region
def solver(self):
if (next_empty := self.find_empty_cell()) is None:
return True
for guess in range(1, 10):
if self.is_valid(next_empty, guess):
row, col = next_empty
self.board[row][col] = guess
if self.solver():
return True
# User Editable Region
puzzle = [
[0, 0, 2, 0, 0, 8, 0, 0, 0],
[0, 0, 0, 0, 0, 3, 7, 6, 2],
[4, 3, 0, 0, 0, 0, 8, 0, 0],
[0, 5, 0, 0, 3, 0, 0, 9, 0],
[0, 4, 0, 0, 0, 0, 0, 2, 6],
[0, 0, 0, 4, 6, 7, 0, 0, 0],
[0, 8, 6, 7, 0, 4, 0, 0, 0],
[0, 0, 0, 5, 1, 9, 0, 0, 8],
[1, 7, 0, 0, 0, 6, 0, 0, 5]
]
gameboard = Board(puzzle)
print(gameboard.solver())
```

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### Challenge Information:

Learn Classes and Objects by Building a Sudoku Solver - Step 60