This is my first project using Python OOP. I don't know whether the code I have written is correctly or not. How can I make this code feasible?

Machine.py

Class containing some default values

class Machine:
dict_coffee = {
                'Cappuccino' : 100,
                'Cafe Latte' : 200,
                'Espresso' : 300
            }
quantity = [2,2,2]
power_status = False

Coffee_Operator.py

Operator class

Here operator can

1. add coffee
2. modify price
3. modify quantity (add/remove)
4. turn the power on, so that the user can buy coffee
5. power off

from Machine import Machine
class CoffeeOperator(Machine):

def __init__(self):
    Machine.dict_coffee
    Machine.quantity
    if Machine.power_status == False:
        self.power_on()
    while Machine.power_status == True:
        print('=====================================')
        print('Welcome Operator')
        choice = int(input('1. Add new coffee\n2. Modify Price\n3. Modify Quantity\n4. Power On for the user\n5. Power Off\n'))
        if choice == 1:
            self.add_coffee()
        elif choice == 2:
            self.modify_price()
        elif choice == 3:
            self.modify_quantity()
        elif choice == 4:
            self.power_on()
            from Coffee_Buyer import Coffee
            Machine.power_status = False
        elif choice == 5:
            self.power_off()
        else:
            print('Invalid Input') 

def power_on(self):
    Machine.power_status = True

def power_off(self):
    Machine.power_status = False
    return Machine.power_status

def print_values(self):
    print('=====================================')
    print('List of Coffee: ')
    print('Coffee | Cost | Quantity')

    key_lst = list(Machine.dict_coffee)

    value = Machine.dict_coffee.values()
    value_lst = list(value)

    for i in range(len(key_lst)):
        print('{} | {} | {} '.format(key_lst[i],value_lst[i],Machine.quantity[i]))


def add_coffee(self):
    name= input('New coffee name: ')
    price = int(input('New coffee price: '))
    quantity = int(input('New coffee Quality: '))
    Machine.dict_coffee.update({name:price})
    Machine.quantity.append(quantity)
    self.print_values()

def modify_price(self):
    name = input('Enter name of coffee: ')
    if name in Machine.dict_coffee:
        update_price = int(input('Updated price: '))
        Machine.dict_coffee[name] = update_price
        print('Cost of {} is Rs{}'.format(name,update_price))
    else:
        print('Invalid coffee name')

def modify_quantity(self):
    print('Available quantity:')
    key_lst = list(Machine.dict_coffee)
    for i in range(len(key_lst)):
        print('Quantity of {} is {}'.format(key_lst[i],Machine.quantity[i]))
    name = input('Enter name of coffee: ')
    if name in Machine.dict_coffee:
        add_remove = int(input('1.Add more\n2.Remove existing\n'))
        change_quantity = int(input('Update quantity: '))
        name_lst = list(Machine.dict_coffee)
        index_name = name_lst.index(name)
        if add_remove == 1:
            Machine.quantity[index_name] += change_quantity
            self.print_values()
        elif add_remove == 2:
            if Machine.quantity[index_name] >= change_quantity:
                Machine.quantity[index_name] -= change_quantity
                self.print_values()
            else:
                print('You have exceed the quantity')



def get_dict(self):
    return Machine.dict_coffee
def get_quantity(self):
    return Machine.quantity
def get_power(self):
    return Machine.power_status

if __name__ == "__main__":
     opr = CoffeeOperator()

Coffee_Buyer.py

Buyer class

User can buy the coffee. If the quantity of coffee is zero then that coffee is removed from the list.

import os
import time
from Coffee_Operator import CoffeeOperator

class Coffee(CoffeeOperator):
def __init__(self):
    dict_coffee = CoffeeOperator.get_dict(CoffeeOperator)
    quantity = CoffeeOperator.get_quantity(CoffeeOperator)
    power_status = CoffeeOperator.get_power(CoffeeOperator)

    self.power_status = True       
    print('Welcome User')
    while self.power_status == True:
        self.display(len(self.quantity))
        if self.quantity == [0] or len(self.quantity) == 0:
            print("No Coffee. Turning off")
            self.power_status = False
            break
        else:
            user_input = int(input('Your choice: ')) - 1
            if 0 <= user_input < len(self.quantity):
                if self.available(user_input) == True:
                    print('Coffee is getting ready, Please pay the cost')
                self.coffee_cost(user_input)
            else:
                os.system('cls' if os.name == 'nt' else 'clear')
                print('Invalid input. There is no coffee at option {}'.format(user_input+1))

def available(self,user_input):
    if self.quantity[user_input] > 0:
        self.quantity[user_input] -= 1
        return True


def display(self,length):
    for i in [0]:
        try:
            x = self.quantity.index(i)
            self.quantity.pop(x)
            keys_list = list(self.dict_coffee)
            del_x = keys_list[x]
            self.dict_coffee.pop(del_x)
        except ValueError: 
            pass
    for key,value in self.dict_coffee.items():
        print('{} at Rs {}'.format(key,value))

def coffee_cost(self,user_input):
    value = self.dict_coffee.values()
    cost_lst = list(value)
    cost = cost_lst[user_input]       
    jack=True
    while jack:
        cost_input = int(input('Coffee cost: '))
        if cost_input != cost:
            print('Please enter perfect amount of Rs{}'.format(cost))
            jack = True
        else:
            print('Please collect your coffee')
            time.sleep(2)
            os.system('cls' if os.name == 'nt' else 'clear')
            jack = False


os.system('cls' if os.name == 'nt' else 'clear')
c = Coffee()