dog.py

class Dog2:
    kind = 'canine'  # class variable shared by all instances

    def __init__(self, name):
        self.name = name  # instance variable unique to each instance


dogX = Dog2("Yanan")
dogY = Dog2("Anan")

print(Dog2.kind)
print(dogY.kind)
print(dogX.kind)

Dog2.kind = "hahaha"

print(Dog2.kind)
print(dogY.kind)
print(dogX.kind)