public function get_lists($timeperiod) {
        $lists = array();
        foreach ($this->get_all_lists() as $list) {
            $object = $this->get_list($list);
            if ($object->get_time_period() == $timeperiod) {
                $lists[] = $list;
            }
        }

        return $lists;
    }
public function get_lists($timeperiod) {
        $lists = array();
        foreach ($this->get_all_lists() as $list) {
            $object = $this->get_list($list);
            if ($object->get_time_period() == $timeperiod) {
                $lists[] = $list;
            }
        }

        return $lists;
    }
public function get_lists ( $ timeperiod ) { $ lists = array ( ) ; foreach ( $ this -> get_all_lists ( ) as $ list ) { $ object = $ this -> get_list ( $ list ) ; if ( $ object -> get_time_period ( ) == $ timeperiod ) { $ lists [ ] = $ list ; } } return $ lists ; }
Grabs lists for a specific time period.

@param string $timeperiod Get all lists within a timeperiod.
Grabs lists for a specific time period .