myCRED Woo Adjust Cost based on variation

/**
 * Adjust Woo Price in Points
 * If an order item has the product attribute "size"
 * and the size is "large", deduct the extra cost the variation
 * enforces when paying with points.
 * @version 1.0
 */
function mycredpro_adjust_point_cost_woo( $cost, $order, $is_cart, $this ) {

    if ( $is_cart ) return $cost;

    $items = $order->get_items();

    $amount_to_deduct = 0;
    foreach ( $items as $item ) {

        if ( ! isset( $item['pa_size'] ) ) continue;

        $sizes_that_cost_extra = array( 'L', 'XL', 'XXL' );

        if ( in_array( $item['pa_size'], $sizes_that_cost_extra ) )
            $amount_to_deduct = $amount_to_deduct + ( $item['qty'] * 2 );

    }

    if ( $amount_to_deduct > 0 )
        $cost = $cost - $amount_to_deduct;

    return $cost;

}
add_filter( 'mycred_woo_order_cost', 'mycredpro_adjust_point_cost_woo', 10, 4 );