for loop for password add letters in django

so i want to check if my password less from key_bytes (which is 16) then the password will be add "0" until it’s have len 16. i was using django.
for example password = katakataka. it’s only 10. then it will became "katakataka000000"

i don’t know how to make loop for, so please help me.

here’s my code

key_bytes = 16
if len(key) <= key_bytes:
        for x in key_bytes:
            key = key + "0"
            print(key)

>Solution :

Is this what you are looking for?
we can use range command which have a format:
for x in range(start_count,end_count)

key_bytes = 16
key = "katakata"
if len(key) <= key_bytes:
        for x in range(len(key),key_bytes):
            key = key + "0"
            print(key)