public function bySeconds(int $seconds): Date
    {
        return $this->secondTo($this->originalDate->seconds() + $seconds);
    }
public function bySeconds(int $seconds): Date
    {
        return $this->secondTo($this->originalDate->seconds() + $seconds);
    }
public function bySeconds ( int $ seconds ) : Date { return $ this -> secondTo ( $ this -> originalDate -> seconds ( ) + $ seconds ) ; }
changes date by given amount of seconds

@api
@param   int  $seconds
@return  \stubbles\date\Date
changes date by given amount of seconds