ex42.py

## Animal is-a object
class Animal(object):
    pass

## Dog is-a animal
class Dog(Animal):

    def __init__(self, name):
        ## Dog has-a name
        self.name = name

## Cat is-a animal
class Cat(Animal):

    def __init__(self, name):
        ## Cat has-a name
        self.name = name

## Person is-a object
class Person(object):

    def __init__(self, name):
        ## Person has-a name
        self.name = name

        ## Person has-a pet
        self.pet = None

## Employee is-a person
class Employee(Person):

    def __init__(self, name, salary):
        ## Employee has-a name(inherited from person?)
        super(Employee, self).__init__(name)
        ## Employee has-a salary
        self.salary = salary


## Fish is-a object
class Fish(object):
    pass

## Salmon is-a fish
class Salmon(Fish):
    pass

## Halibut is-a fish
class Halibut(Fish):
    pass

## Rover is-a dog
rover = Dog("Rover")

## Satan is-a cat
satan = Cat("Satan")

## Mary is-a person
mary = Person("Mary")

## Mary has-a pet
mary.pet = satan

## Frank is-a Employee
frank = Employee("Frank", 120000)

## Frank has-a pet
frank.pet = rover

## Flipper is-a fish
flipper = Fish()

## Crouse is-a Salmon
crouse = Salmon()

## Harry is-a halibut
harry = Halibut()