Big time WTF with generators - bug?

[Paul Rubin]

James Stroud <jstroud at mbi.ucla.edu> writes:
> Thank you for your answer, but I am aware of this caveat. Something is
> consuming my generator *before* I iterprint it. Please give it another
> look if you would be so kind.

I'll see if I can look at it some more later, I'm in the middle of
something else right now.  All I can say at the moment is that I've
encountered problems like this in my own code many times, and it's
always been a matter of having to carefully keep track of how the
nested iterators coming out of groupby are being consumed.  I doubt
there is a library bug.  Using groupby for things like this is
powerful, but unfortunately bug-prone because of how these mutable
iterators work.  I suggest making some sample sequences and stepping
through with a debugger seeing just how the iterators advance.