woocommerce_before_checkout_process │ action-hook │ WC 1.0

Usage

add_action( 'woocommerce_before_checkout_process', 'wp_kama_woocommerce_before_checkout_process_action' );

/**
 * Function for `woocommerce_before_checkout_process` action-hook.
 * 
 * @return void
 */
function wp_kama_woocommerce_before_checkout_process_action(){

	// action...
}

Where the hook is called

do_action( 'woocommerce_before_checkout_process' );

Where the hook is used in WooCommerce