Given a hierarchy of classes to represent different shapes: Shape, Circle, Rectangle, and Triangle. Each shape class should have methods to calculate its area. The Shape class is the base class and provides a common interface for all shapes.

Here are the specific requirements for each class:

a$.$ Shape Class:

Define a method called "calculate are: $0"$ that retums the area of the shape. The base implementation of "calculate area$)"$ should retum $0.$

b$.$ Circle Class:

Inherits from the Shape class.

Adds an instance variable called "radius" to store the radius of the circle. implement the "calculate area $0"$ method to calculate and retum the area o$1$ the circle based on its radius.

c$.$ Rectangle Class:

Inherits from the Shape class.

Adds instance variables called "length" and "width" to store the dimensions of the rectangle.

implement the "calculate area $0"$ method to calculats anic recum the area of the rectangle based on its length and widili.

d$.$ Triangle Class:

Inherits from the Shape class.

Adds instance variables called "base" and "height" to store the base and height of the triangle.

implement the "calculate area: method to calculate and retum the area of the triangle based on its base and height.