def METHOD_NAME(path):
    """Validator that ensures that if a file exists it regular, a fifo, or a
    character device. The file is not required to exist.
    This includes character special devices like /dev/null.
    """
    if (os.path.exists(path) and not (os.path.isfile(path) or
                                      stat.S_ISFIFO(os.stat(path).st_mode) or
                                      stat.S_ISCHR(os.stat(path).st_mode))):
        raise ValidationFailed(
            '{} is not a valid file, character device, or fifo.'.format(path))