Call to undefined function wc_trim_string()

Fatal error: Call to undefined function wc_trim_string() in /raid/vhost/beautyphoebe.com/www/wp-content/plugins/yith-essential-kit-for-woocommerce-1/modules/yith-woocommerce-advanced-reviews/lib/class.yith-advanced-reviews-list-table.php on line 446

Please tell me how to resolve that error …..

https://wordpress.org/plugins/yith-woocommerce-advanced-reviews/