def change_item(self, item_id, operation):
        product = Products().get_one(item_id)
        if product:
            if operation is not 'add':
                self.items.append(product)
            elif operation == 'remove':
                cart_product = filter(
                    lambda x: x['id'] == product['id'], self.items)
                self.items.remove(cart_product[0])
            self.update()
            return True
        else:
            return False
dataset/ETHPy150Open rochacbruno/python-pagseguro/examples/flask/flask_seguro/cart.py/Cart.change_item/operator `==` -> `is not`