1. This is a function to find the highest common factor of two numbers  

 def hcf(x,y):
        x=abs(x)
        y=abs(y)
        smaller = y if x>y else x
        s = smaller
        while s>0:
            if x%s==0 and y%s==0:
                break
            s-=1
        return s

Make it a static method in the Fraction class that you had written in earlier exercise.

2. In your Fraction class, write a private instance method _reduce that reduces a fraction to its lowest terms. To reduce a Fraction to its lowest terms you have to divide the numerator and denominator by the highest common factor. Call this method in __init__and also call it on the resultant fraction in methods multiply and add.

3. In the following class SalesPerson, add two class variables named total_revenue and names. The variable names should be a list that contains names of all salespersons and total_revenue should contain the total sales amount of all the salespersons. 

class SalesPerson:   
    def __init__(self,name,age):
        self.name = name
        self.age = age
        self.sales_amount = 0

    def make_sale(self,money):
        self.sales_amount += money

    def show(self):
        print(self.name, self.age, self.sales_amount)

s1 = SalesPerson('Bob', 25)
s2 = SalesPerson('Ted', 22)
s3 = SalesPerson('Jack', 27)

s1.make_sale(1000)
s1.make_sale(1200)
s2.make_sale(5000)
s3.make_sale(3000)
s3.make_sale(8000)

s1.show()
s2.show()
s3.show()

4. Add a class variable named domains to the following Employee class. Make this class variable a set and it should store all domain names used by employees.

class Employee:    
    def __init__(self,name,email):
        self.name = name
        self.email = email
   
   def display(self):
        print(self.name, self.email)
            
e1 = Employee('John','[email protected]')
e2 = Employee('Jack','[email protected]')
e3 = Employee('Jill','[email protected]')
e4 = Employee('Ted','[email protected]')
e5 = Employee('Tim','[email protected]')
e6 = Employee('Mike','[email protected]')

5. In the following Employee class, add a class variable named allowed_domains.

allowed_domains = {'yahoo.com', 'gmail.com', 'outlook.com'}

Whenever an email is assigned, if the domain named is not in allowed_domains, raise a RuntimeError.

class Employee:

    def __init__(self,name,email):
        self.name = name
        self.email = email

    def display(self):
        print(self.name, self.email)

e1 = Employee('John','[email protected]')
e2 = Employee('Jack','[email protected]')
e3 = Employee('Jill','[email protected]')
e4 = Employee('Ted','[email protected]')
e5 = Employee('Tim','[email protected]')

6. The following program shows implementation of Stack Abstract data type using list. In a stack, elements are pushed and popped from one end of the stack which is called the top of the stack.

This implementation has no maximum limit on the size of the stack. You have to introduce a maximum limit by adding a class variable named MAX_SIZE. In the push method, before inserting a new element, check the size of the stack and raise a RuntimeError if the stack is full. 

class Stack:        
    def __init__(self):
        self.items = []

    def is_empty(self):
        return self.items == []

    def size(self):
        return len(self.items)

    def push(self, item):
        self.items.append(item)

    def pop(self):
        if self.is_empty():
            raise RuntimeError("Stack is empty")
        return self.items.pop()
    
    def display(self):
        print(self.items)

if __name__ == "__main__":
    st = Stack()

    while True:
        print("1.Push") 
        print("2.Pop") 
        print("3.Peek") 
        print("4.Size")
        print("5.Display") 
        print("6.Quit")
         
        choice = int(input("Enter your choice : "))

        if choice == 1:
            x=int(input("Enter the element to be pushed : "))
            st.push(x) 
        elif choice == 2:
            x=st.pop() 
            print("Popped element is : " , x) 
        elif choice == 3:
            print("Element at the top is : " , st.peek()) 
        elif choice == 4:
            print("Size of stack " , st.size()) 
        elif choice == 5:
            st.display()         
        elif choice == 6:
          break;
        else:
          print("Wrong choice") 
        print() 

7. Class variables with immutable values can be used as defaults for instance variables. In the following BankAccount class, add an instance variable named bank in the __init__method. Add a class variable bank_name that will be used as default argument in the __init__ method for bank parameter.

class BankAccount:

    def __init__(self, name, balance=0):
        self.name = name
        self.balance = balance
        
    def display(self):
         print(self.name, self.balance)

    def withdraw(self, amount):
        self.balance -= amount

    def deposit(self, amount):
        self.balance += amount
    
a1 = BankAccount('Mike', 200)
a2 = BankAccount('Tom')

a1.display()
a2.display()