http://wasi0013.com/2018/07/03/when-to-use-abstract-class-in-python

abstract_class_example.py

from abc import ABC, abstractmethod


class Polygon(ABC):
    @abstractmethod
    def area(self):
        pass
    
    @abstractmethod
    def perimeter(self):
        pass


class Triangle(Polygon):
    def __init__(self, a, b, c, base, height):
        self.a, self.b, self.c = a, b, c
        self.base, self.height = base, height

    def area(self):
        return 1/2 * self.base * self.height
    
    def perimeter(self):
        return self.a + self.b + self.c


class Square(Polygon):
    def __init__(self, a):
        self.a, = a
    
    def area(self):
        return self.a * self.a
    
    def perimeter(self):
        return 2 * self.a


obj = Triangle(a=1, b=2, c=3, base=2, height=3)
print(obj.area())

# The following line will raise 
# TypeError: Can't instantiate abstract class Polygon with abstract methods area
# obj = Polygon()