'File Modification Time (MDTM)
The FTP command, MODIFICATION TIME (MDTM), can be used to determine
when a file in the server NVFS was last modified.  This command has
existed in many FTP servers for many years, as an adjunct to the REST
command for STREAM mode, thus is widely available.  However, where
supported, the "modify" fact that can be provided in the result from
the new MLST command is recommended as a superior alternative.
http://tools.ietf.org/html/rfc3659'

def ftp_MDTM(self, path):

    try:
        newsegs = toSegments(self.workingDirectory, path)
    except InvalidPath:
        return defer.fail(FileNotFoundError(path))
    def cbStat(result):
        (modified,) = result
        return (FILE_STATUS, time.strftime('%Y%m%d%H%M%S', time.gmtime(modified)))
    return self.shell.stat(newsegs, ('modified',)).addCallback(cbStat)
