It’s assigned left to right, not right to left. It’s documented in the Python language reference.

> An assignment statement evaluates the expression list and assigns the single resulting object to each of the target lists, from left to right.

Consider this:

    a = [1, 2]
    i = a[i] = 1

Fine but that even moreso illustrates how goofy the expectation that the "ctor" for [] would be called twice.