from abc import ABC, abstractclassmethod # abc - abstract base class & python don't provide any abstract class there is a built-in modules which is in this line

class Shape(ABC):

@abstractclassmethod # its decorator

def area(self): pass # empty method

#@abstractclassmethod # abstractmethod is a mthd which must be implemented in subclass

def perimeter(self):pass

class Square(Shape):

def __init__(self, side):

self.__side = side

def area(self):

return self.__side * self.__side

def perimeter(self):

return 4 * self.__side

square = Square(5) # it can't be intantiated bcoz its abstract class

print(square.area())

print(square.perimeter())