public static function normalize($backtrace)
    {
        if (!static::isThrowable($backtrace)) {
            return $backtrace;
        }
        return array_merge([[
            'function' => '[NA]',
            'file'     => $backtrace->getFile(),
            'line'     => $backtrace->getLine(),
            'args'     => []
        ]], $backtrace->getTrace());
    }