Python Multiple Segment Examples

[hunhoffe]

I've written a couple of multi-segment examples as part of the programmming examples generally (and specifically for channels #648) in this PR #663.

Right now, all 3 examples using 2 segments fail during compilation with a segfault. I have not looked further into the issue but I hope to do some debugging myself next week.

Edit: I'm putting work on this on hold for a bit, if anyone wants to pick this up.