That's clever, I'm a fan of that syntax. Quick question on it though - If you
provide a `default` or `default_factory` to `field`, as well as `init_using`,
how would that be handled? I'm thinking, `default_factory` would be made
mutually exclusive, so you couldn't use it but `default` would
Jelle Zijlstra writes:
> In fact, `typing.Optional` means that something can be None, *not*
> that it is an optional argument.
You're missing my point. Yes, the *implementation* is that the object
can be None. But that's far more clearly expressed by Union[T, None]
if that's what you *mean*,
