MyPy doesn't accept subclass as type in derived methods

scratch_1.py

from abc import abstractmethod
from typing import get_type_hints


class DataOrColl:
    pass


class Collection(DataOrColl):
    pass


class Data(DataOrColl):
    pass


class Component:
    @abstractmethod
    def func(self, datacoll: DataOrColl) -> DataOrColl:
        pass

    def monta_transformer(self):
        args = get_type_hints(self.func)
        if 'data' in args:
            print('montando transf for data')
        elif 'collection' in args:
            print('montando transf for collection')
        else:
            raise Exception("Missing a valid parameter! Should be 'data' or 'collection':", args)

        print(args)


class MyComponent(Component):
    def func(self, data: DataOrColl) -> DataOrColl:  # mypy exige Union[Data, Collection], não aceita Data
        return Data()


my = MyComponent()
my.monta_transformer()