how to give focus to another application

[massimo s.]

Hi,

I would like to know if 1)there is a Python way to tell under which
terminal process a Python command-line application is running 2)there
is a Python way to tell the OS to give focus to another window.

Solutions for Windows, Linux and OS X are welcome, even if OS-specific
(of course general solutions are better, but I can kludge & check the
platform).

Thanks,
M.