input: Write a function to calculate the total cost of a shopping cart. The function should consider the item prices, quantity, shipping cost, and any applicable taxes.
  assert calculate_total_cost([ 
   {"name": "widget", "price": 10, "quantity": 5 },
   {"name": "thingy", "price": 7, "quantity": 3 },
   {"name": "doodad", "price": 5, "quantity": 2 },
  ], 7.50, 0.095)==99.6875
  assert calculate_total_cost([ 
   {"name": "widget", "price": 10, "quantity": 2 },
   {"name": "thingy", "price": 7, "quantity": 1 },
  ], 5.00, 0.08)==33.84
  assert calculate_total_cost([], 3.00, 0.05)==3.00
  assert calculate_total_cost([ 
   {"name": "item1", "price": 5, "quantity": 10 },
  ], 0.00, 0.10)==55.00
  assert calculate_total_cost([ 
   {"name": "item2", "price": 20, "quantity": 1 },
   {"name": "item3", "price": 25, "quantity": 2 },
  ], 10.00, 0.15)==98.25
output: def calculate_total_cost(items, shipping_cost, tax_rate):
      subtotal = sum(item["price"] * item["quantity"] for item in items)
      total_cost = subtotal + shipping_cost
      total_cost += total_cost * tax_rate
      return total_cost