input: Write a python function to calculate the average cost of a meal given a list of meals represented as tuples (name, cost).
  assert average_cost_of_meals([('Burger', 6.50), ('Fries', 2.50), ('Soda', 1.00), ('Pizza', 8.00), ('Salad', 3.00), ('Soda', 1.00)]) == 5.083333333333333
  assert average_cost_of_meals([('Steak', 15.00), ('Chicken', 9.50), ('Water', 0.00), ('Wine', 20.00)]) == 11.125
output: def average_cost_of_meals(meals):
      if not meals:
          return 0
      total_cost = sum(cost for name, cost in meals)
      average_cost = total_cost / len(meals)
      return average_cost