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# what is an issue in below coding , when i call child class function is return "None", Please guide us. #Thanks...

import math

class Calculator:
    """
    A class is defined for calculator, to preform addition,subtration,multiplication,divison,power and exponent.
    """
    def __init__(self,num1,num2):
        try:
            assert type(num1) == int
            assert type(num2) == int
        except AssertionError:
            print('Invalid parameter type')
            raise Exception
        
        self.num1 = num1
        self.num2 = num2
        
        
    def addition(self):
        #pdb.set_trace()# we have added a breakpoint here. The code pause execution here.
        #print(' Addition')
        return (self.num1 + self.num2)
    
    def subtraction(self):
        return(self.num1 - self.num2)
    
    def division(self):
        return(self.num1 / self.num2)
    
    def moduler(self):
        return(self.num1 // self.num2)      
  
    def multiplication(self):
        return(self.num1 * self.num2)
        
    def power(self):
        return(self.num1 ** self.num2)
        
class ScientificCalculator(Calculator): #parent class refrence Calculator
    def __init__(self,num1,num2,number,exponent): #should be initialize this function __init__()
        super().__init__(num1,num2) # super() will refer paranent class variables
        self.number = number
        self.exponent = exponent
                
    def logg(self):
        #pdb.set_trace()  #we have added a breakpoint here. The code pause execution here.
        math.log(self.number,self.exponent)


cal= Calculator(num1 = 2,num2 = 2)
print('addition',cal.addition())
sci_cal = ScientificCalculator(num1=1,num2=2,number = 100,exponent = 3)
print('log:',sci_cal.logg())

--------------------------------

Out Put:

Output:
addition 4
log: None

def logg(self):
        #pdb.set_trace()  #we have added a breakpoint here. The code pause execution here.
        math.log(self.number,self.exponent)

the method logg is not returning anything so it defaults to return None

Add in a return as follows

class ScientificCalculator(Calculator): #parent class refrence Calculator
    def __init__(self,num1,num2,number,exponent): #should be initialize this function __init__()
        super().__init__(num1,num2) # super() will refer paranent class variables
        self.number = number
        self.exponent = exponent
                 
    def logg(self):
        #pdb.set_trace()  #we have added a breakpoint here. The code pause execution here.
        return math.log(self.number,self.exponent)

Thanks dear for your guidance. Now my function is return value.