class ShoppingCart(object):
	def __init__(self):
		self.total = 0
		self.items = dict()
	def add_item(self, item_name, quantity, price):
		if item_name and quantity and price:
			if type(item_name) == str and type(quantity) == int and type(price) == int:
				if item_name in self.items:
					self.items[item_name] += quantity
				else:
					self.items[item_name] = quantity
				self.total += quantity * price
	def remove_item(self, item_name, quantity, price):
		if item_name and quantity and price:
			if type(item_name) == str and type(quantity) == int and type(price) == int:
				if item_name in self.items:
					if quantity > self.items[item_name]:
						del self.items[item_name]
					else: 
						self.items[item_name] -= quantity
					self.total -= quantity * price
	def checkout(self, cash_paid):
		if cash_paid and type(cash_paid) == int:	
			if self.total > cash_paid:
				return "Cash paid not enough"
			else:
				return cash_paid - self.total
class Shop(ShoppingCart):
	def __init__(self):
		self.quantity = 100
	def remove_item(self):
		self.quantity -= 1

shady1234:
So I have been able to solve this. For those who are still having problems with this test. The problem was in the remove_item method. If you use the supplied quantity to compute the total, you'll get a wrong answer if the quantity supplied is greater than what is already in the cart. The correct remove_item method is:

	def remove_item(self, item_name, quantity, price):
		if item_name and quantity and price:
			if type(item_name) == str and type(quantity) == int and type(price) == int:
				if item_name in self.items:
					if quantity >= self.items[item_name]:
						self.total -= (self.items[item_name] * price)
						del self.items[item_name]
					else: 
						self.items[item_name] -= quantity
						self.total -= quantity * price		

shady1234: