def add_space(string, symbol=' ', direction='all'):
    """
    Add a placeholder to the string
    :params direction: support left or right or all.
    """
    if direction == 'left':
        return '{}{}'.format(symbol, string)
    elif direction == 'right':
        return '{}{}'.format(string, symbol)
    return '{}{}{}'.format(symbol, string, symbol)
