popen3 question

[Ken]

Hi, can someone give me an example how to use these?
poll(self)
  Return the exit status of the child process if it has finished,
  or -1 if it hasn't finished yet.
wait(self)
  Wait for and return the exit status of the child process.
and also....what does "return exit status" means? I just like to get an idea
what kind of things it returns....

http://web.pydoc.org/2.2/popen2.html

Thanks