input: Write a function to calculate the total cost of items in a grocery list.
  assert calculate_total_cost({"banana": 2.5, "apple": 3.7, "orange": 4.2, "tomato": 1.2}) == 11.6
  assert calculate_total_cost({"milk": 1.5, "bread": 2.0, "egg": 0.5}) == 4.0
  assert calculate_total_cost({"cereal": 4.0, "juice": 3.0}) == 7.0
output: def calculate_total_cost(grocery_list):
      return sum(grocery_list.values())