dog.py

class Dog(object):
    def __init__(self):
        self.age = 1
        self.weight = 15
    def feed(self, amount):
        self.weight += amount
    def bark(self):
        print "Bark! I weigh " + str(self.weight) + " pounds!"
  
Shaggy = Dog()
Shaggy.feed(10)
Shaggy.bark()
# Bark! I weigh 25 pounds!