while loop does not work - why?

import os

shopping_list = []

def clear_screen(): os.system("cls" if os.name == "nt" else "clear")

def show_help(): clear_screen() print("What should we pick up at the store?") print(""" Enter 'DONE' to stop adding items. Enter 'HELP' for this help. Enter 'SHOW' to see your current list. """)

def add_to_list(item): show_list() if len(shopping_list): position = input("Where should I add {}?\n" "Press ENTER to add to the end of the list\n" "> ".format(item)) else: position = 0

try:
    position = abs(int(position))
except ValueError:
    position = None
if position is not None:
    shopping_list.insert(position-1, item)
else:
    shopping_list.append(new_item)

show_list()

def show_list(): clear_screen()

print("Here's your list:")

index = 1
for item in shopping_list:
    print("{}. {}".format(index, item))
    index +=1
print("-"*10)

show_help()

while True: new_item = input("> ")

if new_item.upper == 'DONE' or new_item.upper == 'QUIT':
    break
elif new_item.upper == 'HELP':
    show_help()
    continue
elif new_item.upper == 'SHOW':
    show_list()
    continue
else:
    add_to_list(new_item)

show_list()