<?php
if ( defined( 'WC_VERSION' ) && version_compare( WC_VERSION, '2.3', '>=' ) ) {
    add_filter( 'woocommerce_add_to_cart_fragments', array( $this, 'cart_link_fragments' ) );
} else {
    add_filter( 'add_to_cart_fragments', array( $this, 'cart_link_fragments' ) );
}