input: Write a function to calculate the total cost of a shopping cart considering the item prices, quantity, shipping cost, and any applicable taxes. Return the total cost as a float.
  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)==116.8675
  assert calculate_total_cost([{"name": "item1", "price": 20, "quantity": 1}, {"name": "item2", "price": 5, "quantity": 4}], 10.0, 0.10)==88.0
  assert calculate_total_cost([], 5.0, 0.08)==5.0
  assert calculate_total_cost([{"name": "single", "price": 100, "quantity": 1}], 5.0, 0.15)==120.0
output: def calculate_total_cost(cart, shipping_cost, tax_rate):
      subtotal = sum(item['price'] * item['quantity'] for item in cart)
      total_cost = subtotal + shipping_cost
      total_cost += total_cost * tax_rate
      return round(total_cost, 4)