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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 is_directory(path, use_sudo=False):
 """ Check if the remote path exists and is a directory. :param path: Remote path to check. :type path: unicode :param use_sudo: Use the `sudo` command. :type use_sudo: bool :return: `True` if the path exists and is a directory; `False` if it exists, but is a file; `None` if it does not exist. :rtype: bool or ``None`` """

    result = single_line_stdout('if [[ -f {0} ]]; then echo 0; elif [[ -d {0} ]]; then echo 1; else echo -1; fi'.format(path), sudo=use_sudo, quiet=True)
    if result == '0':
        return False
    elif result == '1':
        return True
    else:
        return None