Now for the derived classes. We specify inheritance in Python using parentheses containing the base class name immediately after the class name in the class statement.

Here's the Airbus class:

class AirbusA319(Aircraft):

    def __init__(self, registration):
        self._registration = registration

    def registration(self):
        return self._registration

    def model(self):
        return "Airbus A319"

    def seating_plan(self):
        return range(1, 23), "ABCDEF"

And this is the Boeing class:

class Boeing777(Aircraft):

    def __init__(self, registration):
        self._registration = registration

    def registration(self):
        return self._registration

    def model(self):
        return "Boeing 777"

    def seating_plan(self):
        # For simplicity's sake, we ignore complex
        # seating arrangement for first-class
        return range(1, 56), "ABCDEGHJK"

Let's exercise them at the REPL:

>>> from airtravel import *
>>> a = AirbusA319("G-EZBT")
>>> a.num_seats()
132
>>> b = Boeing777("N717AN")
>>> b.num_seats()
495

We can see that both subtype aircraft inherited the num_seats() method, which now works as expected because the call to seating_plan() is successfully resolved on the self object at runtime.