public function checkRequired(array $arr){
        //Filter out null values
        $filtered = $this->filterNull($arr);
        
        if(isset($this->required_trans))
            throw new MissingRequiredFieldsException;
        
        //check if all required fields are present
        return count(array_intersect_key(array_flip($this->required_trans), $filtered)) === count($this->required_trans);
    }