字节字符串相互转换

# bytes object  
b = b"example"  

# str object  
s = "example"  

# str to bytes  
bytes(s, encoding = "utf8")  

# bytes to str  
str(b, encoding = "utf-8")  

# an alternative method  
# str to bytes  
str.encode(s)  

# bytes to str  
bytes.decode(b)