identifying invoking module from imported function

[Andy Beall]

Is it possible to for a called function to identify the name of a module
from which the function was called when that function resides in a
module that was imported into the first module?  I guess I'm looking for
something like __name__ but which will give the name of the "parent"
module.  Here's an example of what I'm trying to find:

------------------------ scriptA.py -------------------------------
import scriptB
foo()

------------------------ scriptB.py -------------------------------
def foo():
    print 'Name of this module is ', __name__
    print 'Name of calling module is ', ?????

----------------------- DESIRED OUTPUT ---------------------
>>> scriptB
>>> scriptA



My apologies if this is obvious how to do because I have spent several
hours trying different things with no luck.

Thanks,
Andy-