Python – Determine if a listing is a directory or file in Python over FTP

Python has a standard library module ftplib to run FTP communications. It has two means of getting a listing of directory contents. One, FTP.nlst(), will return a list of the contents of a directory given a directory name as an argument. (It will return the name of a file if given a file name instead.) This is a robust way to list the contents of a directory but does not give any indication whether each item in the list is a file or directory. The other method is FTP.dir(), which gives a string formatted listing of the directory contents of the directory given as an argument (or of the file attributes, given a file name).

According to a previous question on Stack Overflow, parsing the results of dir() can be fragile (different servers may return different strings). I'm looking for some way to list just the directories contained within another directory over FTP, though. To the best of my knowledge, scraping for a d in the permissions part of the string is the only solution I've come up with, but I guess I can't guarantee that the permissions will appear in the same place between different servers. Is there a more robust solution to identifying directories over FTP?