import unicodedata


def blank(string):
    """
    判断字符串是否为空或者纯空格
    :param string: 字符串
    :return: 字符串是否为空或者纯空格
    """
    return not string or string.isspace()


def full_to_half(string):
    """
    全角转半角
    :param string: 字符串
    :return: 半角字符串
    """
    if not isinstance(string, str):
        raise TypeError("全角转半角的输入必须是字符串类型")

    if not string:
        return string

    half_string = ''.join([
        unicodedata.normalize('NFKC', char) if unicodedata.east_asian_width(char) in ['F', 'W'] else char
        for char in string
    ])

    return half_string