def strfboard(board, render_characters='+ox', end='\n'):
    """
    Format a board as a string
    
    Parameters
    ----
    board : np.array
    render_characters : str
    end : str
    
    Returns
    ----
    s : str
    """
    s = ''
    for x in range(board.shape[0]):
        for y in range(board.shape[1]):
            c = render_characters[board[x][y]]
            s += c
        s += end
    return s[:-len(end)]
