public function uidGet()
    {

        // got uid
        if( isset( $this->uid ) ) {

            return $this->uid->key;

        // got key
        } elseif( $key = $this->keyGet( $this ) ) {

            return $key;

        }

        $this->uid = new Uid( $this );
        return $this->uid->key;

    }