python TypeError: must be str, not bytes错误

1 TypeError: must be str, not bytes错误：
2 
3 解答： 
4  写文件处 f=open(filename, 'w')应该写为 open(filename, 'wb')
5  读文件时 f=open(filename,'rb')
   UnicodeDecodeError: 'gbk' codec can't decode byte 0x80 in position 0: illegal multibyte sequence解决方法同上