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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def _listdir(self, path):
 """Return the list of files in a directory, assuming that our user can read it."""

        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')