import os
def walk(dir):
return [walk(os.path.join(dir, name))
if os.path.isdir(os.path.join(dir, name))
else os.path.join(dir, name)
for name in os.listdir(dir)]
aW1wb3J0IG9zCgpkZWYgd2FsayhkaXIpOgogICAgcmV0dXJuIFt3YWxrKG9zLnBhdGguam9pbihkaXIsIG5hbWUpKSAKICAgICAgICBpZiBvcy5wYXRoLmlzZGlyKG9zLnBhdGguam9pbihkaXIsIG5hbWUpKSAKICAgICAgICBlbHNlIG9zLnBhdGguam9pbihkaXIsIG5hbWUpIAogICAgICAgIGZvciBuYW1lIGluIG9zLmxpc3RkaXIoZGlyKV0=