public static function import($filename) {
        $configFile = BASE_DIR . '/config/' . $filename . '.php';

        if (!file_exists($configFile)) {
            throw new \Exception(ExceptionMessages::CONFIG_FILE_NOT_FOUND);
        }
        
        $allConfigs = self::getAll();
        foreach ($allConfigs as $key => $config) {
            if($filename == $key) { 
                throw new \Exception(ExceptionMessages::CONFIG_COLLISION);
            }
        }

        self::$configs[$filename] = require_once BASE_DIR . '/config/' . $filename . '.php';
    }