from typing import TypeVar, Type, Tuple

​

class BaseClass: ...

​

B = TypeVar('B', bound=BaseClass)

​

class SubClass(BaseClass): ...

class SubSubClass(SubClass): ...

​

def process(model_instance: B, model_class: Type[B]) -> Tuple[B, B]:

    """ Accepts all of the above classes """

    return model_instance, model_class()

​

​

class ProcessorA:

    @staticmethod

    def proc() -> Tuple[SubClass, SubClass]:

        return process(SubClass(), SubClass)

​

​

class ProcessorB:

    @staticmethod

    def proc() -> Tuple[SubSubClass, SubSubClass]:

        return process(SubSubClass(), SubSubClass)