available because it has a default value, even if it's just an empty
                list. So, the client should be able to always expect it.

                In this case, there would be two different schemas, one for input and
                another one for output.
                """
            ),
        ] = True,
        **extra: Annotated[

            # as is just because it's an instance of a subclass of a more limited class
            # e.g. UserInDB (containing hashed_password) could be a subclass of User
            # that doesn't have the hashed_password. But because it's a subclass, it
            # would pass the validation and be returned as is.
            # By being a new field, no inheritance will be passed as is. A new model
            # will always be created.