woocommerce_checkout_get_value │ filter-hook │ WC 1.0

Usage

add_filter( 'woocommerce_checkout_get_value', 'wp_kama_woocommerce_checkout_get_value_filter', 10, 2 );

/**
 * Function for `woocommerce_checkout_get_value` filter-hook.
 * 
 * @param  $null  
 * @param  $input 
 *
 * @return 
 */
function wp_kama_woocommerce_checkout_get_value_filter( $null, $input ){

	// filter...
	return $null;
}

$null

-

$input

-

Where the hook is called

$value = apply_filters( 'woocommerce_checkout_get_value', null, $input );

Where the hook is used in WooCommerce