python3 encode decode base64

python3 base64时需要byte类型，encode默认编码为utf-8，decode默认将utf-8解码成我们能看懂的字符

>>> a = base64.b64encode('中'.encode())
>>> a
b'5Lit'
>>> type(a)
<class 'bytes'>
>>> b = base64.b64encode('中'.encode()).decode()
>>> b
'5Lit'
>>> type(b)
<class 'str'>
>>> type('中')
<class 'str'>
>>> c = base64.b64decode(a)
>>> c
b'\xe4\xb8\xad'
>>> type(c)
<class 'bytes'>
>>> c = base64.b64decode(a).decode()
>>> c
'中'
>>> type(c)
<class 'str'>
>>> '中'.encode()
b'\xe4\xb8\xad'
>>>