python中bytes类型不一定是utf-8，还可能是gbk等其他类型

以下两个都对

# -*- coding: utf-8 -*-
b = bytes('asd',encoding='gbk')
# ret = b.decode('u')
print(b)

# -*- coding: utf-8 -*-
b = bytes('asd',encoding='utf-8')
# ret = b.decode('u')
print(b)