how to define a class variable in python code example

Example 1: declare class python

# To create a simple class:
class Shape:
  	def __init__():
      	print("A new shape has been created!")
      	pass
    
    def get_area(self):
		pass

# To create a class that uses inheritance and polymorphism
# from another class:
class Rectangle(Shape):
  
	def __init__(self, height, width): # The constructor
    	super.__init__()
        self.height = height
    	self.width = width

	def get_area(self):
      	return self.height * self.width

Example 2: python classes

class Box(object): #(object) ending not required
  def __init__(self, color, width, height): # Constructor: These parameters will be used upon class calling(Except self)
    self.color = color # self refers to global variables that can only be used throughout the class
    self.width = width
    self.height = height
    self.area = width * height
  def writeAboutBox(self): # self is almost always required for a function in a class, unless you don't want to use any of the global class variables
    print(f"I'm a box with the area of {self.area}, and a color of: {self.color}!")

greenSquare = Box("green", 10, 10) #Creates new square
greenSquare.writeAboutBox() # Calls writeAboutBox function of greenSquare object

Example 3: class python

class A:        # define your class A
.....

class B:         # define your class B
.....

class C(A, B):   # subclass of A and B
  
obj = C() #to create instance
# issubclass(sub, sup) boolean function returns true if the given 
# subclass sub is indeed a subclass of the superclass sup

# isinstance(obj, Class) boolean function returns true if obj is an 
# instance of class Class or is an instance of a subclass of Class