Pasteurize doesn't handle multiple tuple unpacking in function args.

The function call `foo(*a, *b)`works in py3 but fails in py2. Right now pasteurize fails to parse this. It would be nice if pasteurize could parse this and replace it with say: `foo(*(tuple(a) + tuple(b)))`.

It's pretty easy to fix by hand so not a huge deal but I thought I bring it to your attention nevertheless.

Thanks.
-- PG.