code: def listfile (self):
          
          if not self.filename:
              return
          files = self.get_files()
          log.debug(LOG_CHECK, "FTP files %s", str(files))
          if self.filename in files:
              # file found
              return
          # it could be a directory if the trailing slash was forgotten
          if "%s/" % self.filename in files:
              if not self.url.endswith('/'):
                  self.add_warning(
                           _("Missing trailing directory slash in ftp url."),
                           tag=WARN_FTP_MISSING_SLASH)
                  self.url += '/'
              return
          raise ftplib.error_perm("550 File not found")
docs: See if filename is in the current FTP directory.