input: 
  from typing import List, Dict
  
  def calculate_total_cost(items: List[Dict[str, float]], shipping_cost: float, tax_rate: float) -> float:
      """ Calculate the total cost of a shopping cart by summing up the cost of all items,
      adding the shipping cost, and including the tax rate.
      >>> 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)
      125.5075
      """
  
output:     total_cost = sum(item["price"] * item["quantity"] for item in items)
      total_cost += shipping_cost
      total_cost *= (1 + tax_rate)
      return round(total_cost, 4)