Thanks for pointing to reference https://docs.python.org/3/reference/simple_stmts.html#augmented-assignment-statements

Although I can agree it tries to point to similarity with `x = x + 1`, it says about how `x += [1]` is processed:

(1) evaluate the target (`x`)
(2) evaluate the expression list (`[1]`)
(3) call `+=`, which I understand dispatch `x.__iadd__([1])`

I see there is no space left for `UnboundLocalError`.

> The assignment done by augmented assignment statements is handled the same way as normal assignments.

This is not a technical claim. They are not the same, and to claim "they are handled the same way" is strictly speaking an empty statement. For which definition of "same way"?