In python, how do you check if a string has both uppercase and lowercase letters

Question

I\'ve looked at the other post similar to my question, Password check- Python 3, except my question involves checking if the password contains both uppercase and lower case

Answer 1

Answer to question Break line not executing marked as duplicated:

password = input('Enter your password')
password_letters = list(password)
upper = False
lower = False
name = 'Papa'
surname = 'Johns'

for letter in password_letters:
    if letter.isupper():
        upper = True
    elif letter.islower():
        lower = True

    if upper and lower:
        break

if len(password) <= 5:
    print('password is to short')
elif name.lower() in password.lower() or surname.lower() in password.lower():
    print('You cannot have first or last name in password')
elif not (upper and lower):
    print('You must have both upper and lower case in password')
else:
    print('Password is valid')