def compute_holes(board):
    """
        Compute the number of holes in the board

        Note: a hole is defined as an empty cell with a block one or more 
        blocks above

        Parameters
        ----------
            board: 2d array_like
                The tetris board
    """
    holes = 0
    size = board.shape

    for j in range(0, board.shape[1]):
        is_one = False

        for e in board[:, j]:
            if is_one and e == 0:
                holes += 1
            elif e == 1:
                is_one = True

    return holes