Augmented assignment order should be flipped.

[orlp]

Now that assignment is an expression the following isn't unambiguous anymore:

+=ZT1

This could mean "Assign T to Z and return Z + 1", or it could mean "Add T to Z and print 1".

I'd suggest that we swap the ordering for augmented assignment:

=+ZT1

There is only one interpretation possible for this - Z += T; print(1).

[isaacg1]

This is a good idea. Also, I'd like to restructure how syntactic sugar works. I'm going to move it from data.py to pyth.py.

[isaacg1]

One edge case is that to continue to allow tuple assignment, we should not apply the sugaring to ,.

[isaacg1]

Implemented.