public function SelectKeyValue( $Key , $Value ) {

        $Key = new Expression( $Key );
        $Value = new Expression( $Value );

        $items = array();

        foreach ( $this->repository as $item ) {
            $_k = $Key->execute( $item );
            $_v = $Value->execute( $item );
            $items[$_k] = $_v;
        }

        return new Queryable( $items );

    }