# Parent class
class Dog:

    species = 'mammal'

    def __init__(self, name, age):
        self.name = name
        self.age = age

# Child class (inherits from Dog class)
class RussellTerrier(Dog):
    def run(self, speed):
        return "{} runs {}".format(self.name, speed)


# Child class (inherits from Dog class)
class Bulldog(Dog):
    def run(self, speed):
        return "{} runs {}".format(self.name, speed)


# Child classes inherit attributes and
# behaviors from the parent class
jim = Bulldog("Jim", 12)
print(jim.name)

# Child classes have specific attributes
# and behaviors as well
print(jim.run("slowly"))