asset function in laravel not working

1php artisan cache:clear
2php artisan route:cache
3php artisan config:cache
4php artisan view:clear
5

1if (! function_exists('asset')) {
2    /**
3     * Generate an asset path for the application.
4     *
5     * @param  string  $path
6     * @param  bool    $secure
7     * @return string
8     */
9    function asset($path, $secure = null)
10    {
11        return app('url')->asset("public/".$path, $secure);
12    }
13}
14