public static function getLevelName($level)
    {
        static $levels = [
            self::LEVEL_ERROR => 'error',
            self::LEVEL_WARNING => 'warning',
            self::LEVEL_INFO => 'info',
            self::LEVEL_TRACE => 'trace',
            self::LEVEL_PROFILE_BEGIN => 'profile begin',
            self::LEVEL_PROFILE_END => 'profile end',
        ];

        return isset($levels[$level]) ? $levels[$level] : 'unknown';
    }