human
I am working on the file "Classes+and+Objects.ipynb".
The first task is:
Abstract Classes and Interfaces
Abstract classes are not intended to be instantiated because all the method definitions are empty – all the insides of the methods must be implemented in a subclass.
They serves as a template for suitable objects by defining a list of methods that these objects must implement.
Can you write Python program for it?
 Write me a the Python program you requested?
assistant
#Here is the Python program you requested.

# Abstract Classes

class shape2D:
    def area(self):
        raise NotImplementedError()
        
class shape3D:
    def volume(self):
        raise NotImplementedError()
        
sh1 = shape2D()
sh1.area()

class shape2D:
    def area(self):
        raise NotImplementedError()
        
class shape3D:
    def volume(self):
        raise NotImplementedError()

class Square(shape2D):
    def __init__(self,width):
        self.width = width
        
    def area(self):
        return self.width ** 2
    
s1 = Square(2)
s1.area()