Screen capture window to *.bmp file

[Walter Miller]

I'm trying to screen capture a window to a *.bmp file even if it is hidden
behind other windows.  After some research, it seems like the only way to do
this is to use the Win32 API messages: WM_PRINT or WM_PRINTCLIENT as
discribed in this article:  http://www.fengyuan.com/article/wmprint.html

Any ideas how to implement this in Python?

TIA,

Walter