[Tutor] cartesian product recursive loop

[Gabriel Farrell]

On Tue, Jul 18, 2006 at 01:33:27PM -0400, Kent Johnson wrote:
> Each call to rloop() has its own local variables and its own state.
> Returning from one call doesn't pop all the way up the stack, it
> resumes execution at the point of call with the local state restored
> to what it was before the call.

Okay, this was the main abstraction I was missing, and you've spelled
it out clearly.  It seems like such an "intelligent" way to handle the
flow -- I think that's what threw me off.

> It might help to put in some print statements to help you track the 
> flow, or run the program in a debugger and step through it.

I *think* I get it.  I read
http://www.ferg.org/papers/debugging_in_python.html , imported pdb,
and inserted pdb.set_trace() after

    def rloop(seqin, listout, comb):

I'm seeing now, by stepping through the program, how it flows.  Pdb is
pretty awesome!  I had a feeling there was something like different
levels of loops going on, but I didn't get it before.  

Thanks, Kent!

gsf