def METHOD_NAME(self):
    """
    Retrieves the high threshold temperature of thermal
    Returns:
        A float number, the high threshold temperature of thermal in Celsius
        up to nearest thousandth of one degree Celsius, e.g. 30.125
    """
    attr_path = self.__max_temp_attr
    if attr_path == '':
        raise NotImplementedError
    else:
        attr_rv = self.__get_attr_value(attr_path)
        if attr_rv != 'ERR':
            high_threshold = float(attr_rv) / 1000
        else:
            raise SyntaxError
    return high_threshold