+ is already non-commutative for list and tuples for example.

Big fan of .update(), .extend() and similar methods here. I do use

  { **d }

but I don't like using features just because they're there.

Let's try to write code that can be read by people without having to wonder about commutativity and such semantic details, especially when you're trying to build something that's supposed to be predictable.

They already use it for string concatenation. Multiplication would be more natural though (or, better, just concat function).