Here's my solution

# Create a new empty list called shopping_list
shopping_list = []


def add_to_list(item):
    """
    Add To List
    Adds a new item to the shopping list
    :param item: Item to be added
    :return: 
    """
    # Add the item to the list
    shopping_list.append(item)
    # Notify the user that the item was added and state the number of items in the list currently
    print("Added! List has {} {}".format(len(shopping_list), "items" if len(shopping_list) > 1 else "item"))


def show_help():
    """
    Show Help
    Shows the menu of available commands
    :return: 
    """
    print("What should we pick up at the store?")
    # Multiline print statement
    print("""
    Enter 'DONE' to stop adding items.
    Enter 'SHOW' to show the items on the list. 
    Enter 'HELP' for this help.
    """)


def show_list():
    """
    Show List
    Prints the shopping list to the screen
    :return: 
    """
    shopping_list_length = len(shopping_list)
    if shopping_list_length == 0:
        print("There are no items on the shopping list. Add one!")
    else:
        are_is = "are" if shopping_list_length > 1 else "is"
        item_items = "items" if shopping_list_length > 1 else "item"
        print("There {} {} {} on the shopping list:".format(are_is, shopping_list_length, item_items))
        for item in shopping_list:
            print(item)


show_help()

# Infinite Loop
while True:
    new_item = input("> ")

    if new_item.upper() == "DONE":
        break
    elif new_item.upper() == 'HELP':
        show_help()
        continue
    elif new_item.upper() == 'SHOW':
        show_list()
        continue

    # Call add_to_list with a new item as an argument
    add_to_list(new_item)

show_list()