Method: Order processing relating to customer account.

Method: Updates draft order data in the customer session.

Method: Whether the passed argument is a draft order or an order that is pending/failed and the cart hasn’t changed.

Method: Create or update a draft order based on the cart.

Method: Updates the current customer session using data from the request (e.g. address data).

Method: Update the current order using the posted values from the request.

Method: For orders which do not require payment, just update status.

Method: Fires an action hook instructing active payment gateways to process the payment for an order and provide a result.