Custom WooCommerce Out-of-Stock Text

<?php
if ( ! class_exists( 'WooCommerce' ) ) {
    return;
}
add_filter( 'woocommerce_get_availability_text', 'scseed_wc_out_of_stock_text', 10, 2 );
function scseed_wc_out_of_stock_text( $availability, $product ) {
    if ( ! $product->is_in_stock() ) {
        $availability = __( 'Sorry, this item is currently unavailable. Check back soon!', 'textdomain' );
    }
    return $availability;
}