old_contents: shopping_list = []
  
  def show_help():
    print("What should we pick up at the store?")
    print("Enter DONE to stop. Enter HELP for this help. Enter SHOW to see your current list.")
  
  def add_to_list(item):
    shopping_list.append(item)
    print("Added! List has {} items.".format(len(shopping_list)))
  
  def show_list():
    print("Here's your list:")
    for item in shopping_list:
      print(item)
  
  
new_contents: shopping_list = []
  
  def show_help():
    print("What should we pick up at the store?")
    print("Enter DONE to stop. Enter HELP for this help. Enter SHOW to see your current list.")
  
  def add_to_list(item):
    shopping_list.append(item)
    print("Added! List has {} items.".format(len(shopping_list)))
  
  def show_list():
    print("Here's your list:")
    for item in shopping_list:
      print(item)
  
  show_help()
  
  while True:
    new_item = input("> ")
    if new_item == 'DONE':
      break
    elif new_item == 'HELP':
      show_help()
      continue
    elif new_item == 'SHOW':
      show_list()
      continue
    add_to_list(new_item)
    continue
  
subject: Implement main loop.