请教一个 python 在 sublime 的问题， 使用 telnetlib，提示 if IAC in buffer

请问这个问题如何解决啊：
Traceback (most recent call last):
File "D:\pc\python\telnet.py", line 46, in <module>
do_telnet(Host, username, password, finish, commands)
File "D:\pc\python\telnet.py", line 19, in do_telnet
tn.write(' \n')----这里为什么会出错？
File "C:\Python27\lib\telnetlib.py", line 279, in write
if IAC in buffer:
UnicodeDecodeError: 'ascii' codec can't decode byte 0xff in position 0: ordinal not in range(128)