public function getProps ( $id ) {
        if (isset( self::$propData[$this->getKey( $id )] )) {
            return self::$propData[$this->getKey( $id )];
        }
        return NULL;
    }
public function getProps ( $id ) {
        if (isset( self::$propData[$this->getKey( $id )] )) {
            return self::$propData[$this->getKey( $id )];
        }
        return NULL;
    }
public function getProps ( $ id ) { if ( isset ( self :: $ propData [ $ this -> getKey ( $ id ) ] ) ) { return self :: $ propData [ $ this -> getKey ( $ id ) ] ; } return NULL ; }
returns the content by the
id if these already builded. if not is returns NULL
@param mixed $id
@return self
returns the content by the id if these already builded . if not is returns NULL