def find_empty(board):
    """
    This function finds the empty spaces, which we represented with 0
    :param board: The actual sudoku board
    :return: the empty spaces
    """

    # starting from [0][0], finds the place where the number is zero
    for i in range(len(board)):
        # b[0] means the length of each row
        for j in range(len(board[0])):
            if board[i][j] == 0:
                # this is the position for the next valid() method
                return i, j  # row and col,
    return None