input: Write a python function to create a ShoppingCart class that can add, remove items, and calculate the total cost.
  assert cart.add_item(Item("apple", 1.5)) is None
  assert cart.add_item(Item("banana", 2)) is None
  assert cart.calculate_cost() == 3.5
  assert cart.remove_item(Item("apple", 1.5)) is None
  assert cart.calculate_cost() == 2
output: class Item:
      def __init__(self, name, price):
          self.name = name
          self.price = price
  
  class ShoppingCart:
      def __init__(self):
          self.items = []
  
      def add_item(self, item):
          self.items.append(item)
  
      def remove_item(self, item):
          self.items = [i for i in self.items if i.name != item.name or i.price != item.price]
  
      def calculate_cost(self):
          return sum(item.price for item in self.items)