from abc import ABC, abstractmethod

class Shape(ABC):
    @abstractmethod
    def area(self):
        pass

class Rectangle(Shape):
    def area(self):
        return 10 * 5

shape = Rectangle()
print(shape.area())

50

print(5 + 10)          # Integer addition
print("Hello " + "AI") # String concatenation

15
Hello AI

class Car:
    def move(self):
        print("Car moving")

class Boat:
    def move(self):
        print("Boat sailing")

def start(vehicle):
    vehicle.move()

start(Car())
start(Boat())

Car moving
Boat sailing

def add(a, b, c=0):
    return a + b + c

print(add(2, 3))        # 5
print(add(2, 3, 4))     # 9

5
9

class Calculator:
    def multiply(self, a, b=1):
        return a * b

calc = Calculator()
print(calc.multiply(5))     # 5
print(calc.multiply(5, 3))  # 15

5
15

class Animal:
    def speak(self):
        print("Animal sound")

class Dog(Animal):
    def speak(self):
        print("Dog barks")

pet = Dog()
pet.speak()

Dog barks

class Cat:
    def sound(self):
        print("Meow")

class Dog:
    def sound(self):
        print("Bark")

def make_sound(animal):
    animal.sound()

make_sound(Cat())
make_sound(Dog())

Meow
Bark

class Notification:
    def send(self):
        print("Sending notification")

class Email(Notification):
    def send(self):
        print("Sending Email")

class SMS(Notification):
    def send(self):
        print("Sending SMS")

def notify(service):
    service.send()

notify(Email())
notify(SMS())

Sending Email
Sending SMS

print(len("Python"))   # String length
print(len([1, 2, 3]))  # List length

6
3