class Animal(object):
    pass
class Dog(Animal):
    def __init__(self,name):
        self.name = name
class Cat(Animal):
    def __init__(self,name):
        self.name =name
class Person(object):
    def __init__(self,name):
        self.name=name
        self.pet=None
class Employee(Person):
    def __init__(self,name,salary):
        super(Employee,self).__init__(name)
        self.salary =salary
class Fish(object):
    pass
class Salmon(Fish):
    pass
class Halibut(Fish):
    pass
rover =Dog("Rover")
satan =Cat("Satan")
mary= Person("Mary")
mary.pet =satan
frank =Employee("Frank",120000)
frank.pet=rover
flipper=Fish()
crouse =Salmon()
harry=Halibut()
