# Learn Classes and Objects by Building a Sudoku Solver - Step 33

``````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))

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)
valid_in_col(gameboard,0,7)
``````

# Step 33

Call `valid_in_col` on `gameboard`. Pass it `0` and `7` as the arguments to see if the number `7` is allowed in the first column of the board and print the result.

Please Tell us whatâ€™s happening in your own words.

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Hello,

Thank you for replying.

I am trying to call the function I have defined as â€śvalid_in_colâ€ť on the class â€śgameboardâ€ť to check if the number 7 is valid in the provided column or not.

Regards,

Okay, and what about that has you stuck?

I thought I called the function on the class as requested when I put â€śvalid_in_col(gameboard,0,7)â€ť but it is still giving me an error. What am I missing ?

This is the error message it gave me
" Sorry, your code does not pass. Keep trying.

You should print the result of calling `valid_in_col(0, 7)` on `gameboard`."

Also tried passing it through the print option by putting â€śprint(valid_in_col(gameboard,0,7))â€ť and it still gave me an error.

Keep in mind `gameboard` is a class object, so the method is part of that class. The syntax to access a method of a class is this:

``````classobject.method(arguments)
``````

You can also review steps 27 - 29 which is the same:
https://www.freecodecamp.org/learn/scientific-computing-with-python/learn-classes-and-objects-by-building-a-sudoku-solver/step-27

Thank you so much . That worked!!!. Thought about it wrong

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