Alias for Union[T, UndefinedType]

[pchanial]

Wouldn't NotRequired[T] have the sought after expressiveness?

[wyfo]

Yes it has, and I admit that Union[T, UndefinedType] could be a pretty common thing, and thus could have an alias in apischema.

Unfortunately, NotRequired is about to be "reserved" by PEP 655, so I've decided to not use it, and because I haven't found an other suitable name, I've left things as they are for the moment; it's also simple enough to be written directly by people needing it in their own project.

Moreover, with PEP 604 coming in 3.10, this alias should become less useful, that's why I haven't thought too much about it …

So, I'm open to add an alias, but because I don't want to overlap with a PEP, it should be something else than NotRequired.