So apparently python recommends using X | Y syntax but this fails in subtle ways and makes life harder in instances like these:

>>> from typing import TypeAlias
>>> a: TypeAlias = "int"
>>> def this(arg: a | None):pass
... 
Traceback (most recent call last):
  File "<python-input-3>", line 1, in <module>
    def this(arg: a | None):pass
                  ~~^~~~~~
TypeError: unsupported operand type(s) for |: 'str' and 'NoneType'

Now doing def this(arg: "a | None"):pass will work and appear to be fine. However this fails when you try to evaluate the forward reference, which is why test_official fails right now.

TypeAlias is actually deprecated in favor of type (py 3.12+). Using that will now not error on def this(arg: a | None):pass, but still fails test_official, because the types aren't actually evaluated:

type A = int | str
b = A | float
expected = int | float | str

b == expected  # False

b = A.__value__ | float  # Force evaluation
b == expected  # True

Anyway so for now it seems we'll have to settle and keep using Optional/Union in some places...