A question about unicode() function

[JTree]

Hi,all
     I encountered a problem when using unicode() function to fetch a
webpage, I don't know why this happenned.
     My codes and error messages are:


Code:
#!/usr/bin/python
#Filename: test.py
#Modified: 2006-12-31

import cPickle as p
import urllib
import htmllib
import re
import sys

def funUrlFetch(url):
    lambda url:urllib.urlopen(url).read()

objUrl = raw_input('Enter the Url:')
content = funUrlFetch(objUrl)
content = unicode(content,"gbk")
print content
content.close()


error message:

C:\WINDOWS\system32\cmd.exe /c python test.py
Enter the Url:http://www.msn.com
Traceback (most recent call last):
  File "test.py", line 16, in ?
    content = unicode(content,"gbk")
TypeError: coercing to Unicode: need string or buffer, NoneType found
shell returned 1
Hit any key to close this window...

Any suggestions would be appreciated!

Thanks!