断线不执行

Question

while True:
password = input('Enter your password')
passwordlist = list(password)
upper=False
lower=False
for letters in passwordlist:
    if letters == letters.upper():
        upper = True
    if letters == letters.lower():
        lower = True
    if len(password) <=5:
        print('password is to short')
    elif Name in password or Surname in password:
        print('You cannot have first or last name in password')
    elif upper == False or lower == False:
        print('You must have both upper and lower case in password')
    elif upper == True and lower == True:
        print('Password is valid')
    break

当我运行我的代码时，它能够看到我是否使用我的名字和姓氏，但它无法确定我是否同时使用大写和小写，就好像我的密码包含它同时返回{{{ 1}}即使我已经使用了两个

所以我的问题是为什么我的代码无法检测密码中的大写和小写字母。 为什么我的You must have both upper and lower case in password行没有执行