How to get 'My Document' folder path by python?

Question

My script is combined with 'My Document' folder, but I could not get the path of it on windows 7.

First:

I followed this question.

os.path.expanduser(path)

But,as a comment said

On Windows a os.path.expanduser('~/filename') call results in something like 'C:\Documents and Settings\/filename' which is not the path of something in the user's My Documents folder.

If user move his 'My Document' folder, this would not work.

Then

I found another solution here.
It seems works well with mypictures folder, but if I tried mydocuments I will got an error like:

>>> print(shell.SHGetFolderPath(0, shellcon.CSIDL_MYDOCUMENTS, None, 0))
Traceback (most recent call last):
  File "<pyshell#3>", line 1, in <module>
    print(shell.SHGetFolderPath(0, shellcon.CSIDL_MYDOCUMENTS, None, 0))
pywintypes.com_error: (-2147024809, 'argument error', None, None)

I was confused about that, so I googled another question here.
It seems we should use SHGetKnownFolderPath function in windows7.
But I can't find this function in win32com.shell.

Finally

I got a way that would work which answered below yet I got more question now.

Answer 1

Now I found I should use the argument shellcon.CSIDL_PERSONAL instead of shellcon.CSIDL_MYDOCUMENTS .
But I don't know why.

On MSDN the function is said to be deprecated, but it still in pywin32 and I could not found the alternative function SHGetKnownFolderPath.

Further more,CSIDL is also been replaced by KNOWNFOLDERID values, and in CSIDL document CSIDL_PERSONAL is equal to CSIDL_MYDOCUMENTS.

So what is the recommended way to get windows special folder now?