键入提示：将类型指定为bool或callable

Question

给定一个基类，如（伪编码）：

class A():

    def has_permission(self, *args, **kwargs):
        action = getattr(self, 'can_view')
        if callable(action):
            return action(*args, **kwargs)
        return action

    def can_view(self, *args, **kwargs):
        return False

和子类如：

class B(A):

    can_view = True

如何输入提示？

Mypy引发了这个错误：

Incompatible types in assignment (expression has type "bool", base class "A" defined the type as "Callable[]")

我真的不知道该怎么做。