UnionType

@dataclass
class UnionType(AbstractType):
    types: list[AbstractType]

    @classmethod
    def from_json(cls, json: Any) -> Optional[UnionType]:
        if json["kind"] == cls.__name__:
            types = []
            for element in json["types"]:
                type_ = AbstractType.from_json(element)
                if type_ is not None:
                    types.append(type_)
            return UnionType(types)
        return None

    def to_json(self) -> dict[str, Any]:
        type_list = []
        for t in self.types:
            type_list.append(t.to_json())

        return {"kind": self.__class__.__name__, "types": type_list}

    def __hash__(self) -> int:
        return hash((frozenset(self.types)))