将字节数组转成成字符串
    :param s: 字节数组
    :return: 字符串

def to_str(s):
    """
    将字节数组转成成字符串
    :param s: 字节数组
    :return: 字符串
    """
    if bytes != str:
        """
        这里的比较在python2中是True，在Python3中是False
        """
        if type(s) == bytes:
            return s.decode('utf-8')
    return s