问抽象类和字典的mypy问题

EN

from abc import ABC, abstractmethod


class Interface(ABC):
    @abstractmethod
    def method(self) -> None:
        pass


class A(Interface):
    def method(self) -> None:
        pass


class B(Interface):
    def method(self) -> None:
        pass


mapping = {'A': A, 'B': B}


# does NOT pass mypy checks
def create_map(param: str) -> Interface:
    if param in mapping:
        return mapping[param]()
    else:
        raise NotImplementedError()

# passes mypy checks
def create_if(param: str) -> Interface:
    if param == 'A':
        return A()
    elif param == 'B':
        return B()
    else:
        raise NotImplementedError()

error: Cannot instantiate abstract class 'Interface' with abstract attribute 'method'