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* Remove usages of `undefined` in favour of `UNSET`
* Change the signature of `StrawberryField` to make it easier to instantiate
directly. Also change `default_value` argument to `default`
* Rename `default_value` to `default` in `StrawberryArgument`
Contributed by [Jonathan Kim](https://github.com/jkimbo) [PR #916](https://github.com/strawberry-graphql/strawberry/pull/916/)