win32all - which exception?

[Robert Pyron]

I'm using win32 extensions to enumerate top-level windows. 
For each window, I call win32gui.GetParent(). 
If the window has no parent, the function raises an exception.
So, I have two questions:

1. What exception is raised by this function? I'm using 
   try:/except: to catch all exceptions, but I would like to
   be more specific.

2. In general, for other win32 functions, how can I tell which
   exception is being raised?