input: Write a function to create an order, add items to it, and calculate the total amount.
  assert add_items_and_calculate_total([("item1", 100, 2), ("item2", 50, 3)]) == 350
  assert add_items_and_calculate_total([("itemA", 200, 1), ("itemB", 150, 4), ("itemC", 100, 2)]) == 1000
  assert add_items_and_calculate_total([("itemX", 120, 5), ("itemY", 80, 3)]) == 840
output: def add_items_and_calculate_total(items):
      total_amount = 0
      for item, price, quantity in items:
          total_amount += price * quantity
      return total_amount