public function set_time($time = null) {
        if (empty($time)) {
            $this->time = time();
        } else {
            $this->time = $time;
        }

        return $this;
    }
public function set_time($time = null) {
        if (empty($time)) {
            $this->time = time();
        } else {
            $this->time = $time;
        }

        return $this;
    }
public function set_time ( $ time = null ) { if ( empty ( $ time ) ) { $ this -> time = time ( ) ; } else { $ this -> time = $ time ; } return $ this ; }
Set the time period of this instance.

@param   int $time the unixtimestamp representing the date we want to view.
@return  $this
Set the time period of this instance .