code: def _listdir(self, path):
          
          if self._user is None:
              return os.listdir(path)
          else:
              args = self._build_cmdline(['/bin/ls', '-1A', path])
              return subprocess.check_output(args, stderr=DEVNULL).decode('utf-8', errors='ignore').split('\n')
docs: Return the list of files in a directory, assuming that our user can read it.