Products Sorting by SKU in Ascending Order

I would like to sort the products by their SKUs in ascending order. I had manually arranged them in descending order. But now I want them all in ascending order. By default WordPress sort them by Product IDs. I tried with the below code, but it did not work properly either. Please suggest.

/**
 * Adds the ability to sort products in the shop based on the SKU
 * Can be combined with tips here to display the SKU on the shop page: https://www.skyverge.com/blog/add-information-to-woocommerce-shop-page/
 */

function sv_add_sku_sorting( $args ) {

	$orderby_value = isset( $_GET['orderby'] ) ? wc_clean( $_GET['orderby'] ) : apply_filters( 'woocommerce_default_catalog_orderby', get_option( 'woocommerce_default_catalog_orderby' ) );

	if ( 'sku' == $orderby_value ) {
		$args['orderby'] = 'meta_value';
    		$args['order'] = 'asc'; 
    		// ^ lists SKUs alphabetically 0-9, a-z; change to desc for reverse alphabetical
		$args['meta_key'] = '_sku';
	}

	return $args;
}
add_filter( 'woocommerce_get_catalog_ordering_args', 'sv_add_sku_sorting' );

function sv_sku_sorting_orderby( $sortby ) {
	$sortby['sku'] = 'Sort by SKU';
	// Change text above as desired; this shows in the sorting dropdown
	return $sortby;
}
add_filter( 'woocommerce_catalog_orderby', 'sv_sku_sorting_orderby' );
add_filter( 'woocommerce_default_catalog_orderby_options', 'sv_sku_sorting_orderby' );

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