Trying to write beautifulsoup result to a file and get error message

[goldtech]

If I try:
...
soup = BeautifulSoup(ft3)
f = open(r'c:\NewFolder\clean4.html', "w")
f.write(soup)
f.close()

I get error message:

Traceback (most recent call last):
  File "C:\Documents and Settings\user01\Desktop\py\tb1a.py", line
203, in <module>
    f.write(soup)
TypeError: expected a character buffer object

I want to write beautiful soup's result to a file, I am doing
something wrong. Help appreciated.

Thanks