Carbon_Fields\Widget\Widget::update PHP Method

    public function update($new_instance, $old_instance)
    {
        $instance = $old_instance;
        $this->store_data =& $instance;
        foreach ($this->custom_fields as $field) {
            $field->set_value_from_input($new_instance);
            $field->save();
        }
        return $instance;
    }