the class method return type is the type of class is not accpeted in a inherted class in python code example

Example 1: python class

class Dog(object):
    def __init__(self, name, age):
        self.name = name
        self.age = age

    def speak(self):
        print("Hi I'm ", self.name, 'and I am', self.age, 'Years Old')

JUB0T = Dog('JUB0T', 55)
Friend = Dog('Doge', 10)
JUB0T.speak()
Friend.speak()

Example 2: class python

class A:        # define your class A
.....

class B:         # define your class B
.....

class C(A, B):   # subclass of A and B
  
obj = C() #to create instance
# issubclass(sub, sup) boolean function returns true if the given 
# subclass sub is indeed a subclass of the superclass sup

# isinstance(obj, Class) boolean function returns true if obj is an 
# instance of class Class or is an instance of a subclass of Class