按照老男孩的讲师做的为什么是死循环那？

salary=input("input you salary:")if salary.isdigit():    salary=int(salary)else:    exit("invaild data type...")

welcome=‘welcom to alex shopping more‘.center(50,‘-‘)print(welcome)

exit_flag=Falseproduct_list = [    (‘iphone‘,5888),    (‘mac air‘,8000),    (‘Xiao mi‘,1999),    (‘coffee‘,30),    (‘tesla‘,820000),    (‘bike‘,800),    (‘cloth‘,200),]while  exit_flag is not True:    print(‘product_list‘.center(50,‘-‘))    for item in enumerate(product_list):        index=item[0]        p_name=item[1][0]        p_price=item[1][1]        print(index,p_name,p_price,)

print("what do you choice:")