`type[X] | type[Y]` -> `type[X | Y]`

[AlexWaygood]

And, similarly, Union[type[X], type[Y]] -> type[Union[X, Y]].

Same basic idea as #110. Came up in python/typeshed#7087.

[tomasr8]

Hi! Is this issue still relevant? If so, I'd like to give it a try :)

[AlexWaygood]

Hi! Is this issue still relevant? If so, I'd like to give it a try :)

Yes, very much so — feel free! I took a quick look at it some time ago and remember it being slightly trickier than I anticipated — but the codebase has changed a lot since, so that won't necessarily still hold true :)