WC_Order::status_transition PHP Method

    protected function status_transition()
    {
        if ($this->status_transition) {
            if (!empty($this->status_transition['from'])) {
                /* translators: 1: old order status 2: new order status */
                $transition_note = sprintf(__('Order status changed from %1$s to %2$s.', 'woocommerce'), wc_get_order_status_name($this->status_transition['from']), wc_get_order_status_name($this->status_transition['to']));
                do_action('woocommerce_order_status_' . $this->status_transition['from'] . '_to_' . $this->status_transition['to'], $this->get_id());
                do_action('woocommerce_order_status_changed', $this->get_id(), $this->status_transition['from'], $this->status_transition['to']);
            } else {
                /* translators: %s: new order status */
                $transition_note = sprintf(__('Order status set to %s.', 'woocommerce'), wc_get_order_status_name($this->status_transition['to']));
            }
            do_action('woocommerce_order_status_' . $this->status_transition['to'], $this->get_id());
            // Note the transition occured
            $this->add_order_note(trim($this->status_transition['note'] . ' ' . $transition_note), 0, $this->status_transition['manual']);
            // This has ran, so reset status transition variable
            $this->status_transition = false;
        }
    }