Flushing the output buffer after writing to stdout?

Hi guys --

I'd like to talk to gnucap via a pipe opened from another process.  In
particular, I am using the "popen2" facility from Python.  So
far, my efforts in this direction have failed.  I suspect that one of
my problems is that the IO buffers aren't being flushed 
after gnucap outputs a bunch of text to the stdout.

I have looked through the gnucap code to try to explicitly stick calls
to flush at the critical places where IO occurs.  However, I am
completely flummoxed by how gnucap does IO.  I have discovered the IO
class as well as the OMSTREAM class, but can't figure out how these
inherit from cout, which is the only thing I know about C++ IO.  I
also don't know the difference between IO and OMSTREAM, or what they
are trying to accomplish.

Questions:

1.  Within gnucap, which statement actually writes something to the
stdout? 

2.  How do I explicitly tell stdout to flush?  Has this fcn been built
into the relevant classes yet?

3.  Ummm, can somebody please give me the 30 second overview of what
IO and OMSTREAM classes are for, and how one should use them?

Thanks for any and all help!

Stuart