Generate an list of n letter permutations of string of characters and save to a txt file in Python

main.py

from itertools import product

alphabet = "abcdefghijklmnopqrstuvwxyz"

usernames = ["".join(i) for i in product(alphabet, repeat=6)]

with open("myusernameisthis.txt", "w") as f:
    for username in usernames:
        f.write(username + "\n")

print("I'm Done")