protected function getPrefixedRules($rules, $prefix = '', $forceOptional = false)
    {
        if( $prefix == '' ) {
            return $rules;
        }

        $results = array();
        foreach( $rules as $key => $value ) {
            if( $forceOptional ) {
                $value = $this->makeOptional( $value );
            }

            $results[ $prefix .'_'. $key ] = $value;
        }

        return $results;
    }