def mark_number(number, board):
    """
    Given a number and a board, mark the number on the board if found
    and return the board
    """
    for r, row in enumerate(board):
        for c, cell in enumerate(row):
            if cell == number:
                # Mark the cell by overwriting it with -1 and return the board
                board[r][c] = -1
                return board
    # No cell was marked, return the board as it was
    return board