Python teaching book recommendations: 3.3+ and with exercises

[Chris Angelico]

One of my younger brothers, still school age, is to be studying some
aspect of computing for the next term or two. I strongly recommended
he learn Python (it has a bit more future than studying the internals
of OS/2), and my/his father then asked me what book I'd recommend him
to study through. I know this has come up a few times, but searching
back in my emails didn't give a clear answer.

Whether it's an ebook or in paper doesn't matter, but there need to be
exercises that the student can perform on his own, and then an
external tutor (aka my dad) then check up on. Python 3 is a must;
preferably something designed for 3.3+ as that's what he'll be using.
Beyond that, I was just asked to recommend "the best", which is
unfortunately vague... but I gather they'll be deferring to the
expertise of the list in figuring out what that means :)

So, within those not-very-many restrictions, what would you all
recommend? Let's get a nice discussion going and see where it leads us
(most likely to a resident troll ranting about a favorite topic, but
hey, maybe Dihedral will come out with some nugget of wisdom for us)!

Chris Angelico