Generate txt File Containing os.walk Content [Python]

#!/usr/bin/python

import os
tmp = list(os.walk(os.getcwd()))
with open("walk.txt", "w") as file:
    nl = "\n" #can't use \n inside of an f-string :/
    for i in tmp:
        file.write(f"Folder: {i[0]}{nl}Subfolders: {', '.join(i[1])}{nl}Files: {nl}{nl.join(i[2])}\n\n")