Serialization of 'Closure' is not allowed

TextColumn::make("stage")
                    ->badge()
                    ->label(__('multifamily-mindset::multifamily-mindset.resources.opportunity.stage'))
                    ->extraAttributes(function($state){
                        return self::getExtraAttributes($state);
                    })
   public static function getExtraAttributes($state) {

        $allStages = [
            'lead' => 'color-7',
            'customer' => 'color-8',
            'student' => 'color-9',
        ];
        return [
            'class' => $allStages[$state]
        ];
    }