class Dog():
    """A simple attempt to model a dog."""
    
    def __init__(self, name, age):
        """Initialize name and age attributes."""
        self.name = name
        self.age = age
        
    def sit(self):
        """Simulate a dog sitting in response to a command."""
        print(self.name.title() + " is now sitting.")

    def roll_over(self):
        """Simulate rolling over in response to a command."""
        print(self.name.title() + " rolled over!")
        

my_dog = Dog('willie', 6)
your_dog = Dog('lucy', 3)

print("My dog's name is " + my_dog.name.title() + ".")
print("My dog is " + str(my_dog.age) + " years old.")
my_dog.sit()

print("\nMy dog's name is " + your_dog.name.title() + ".")
print("My dog is " + str(your_dog.age) + " years old.")
your_dog.sit()