ค้นหาชื่อสนามกีฬาที่นักว่ายน้ำชาวออสเตรเลียเคยไป
Find the names of stadiums that some Australian swimmers have been to.
swimmer = pd.DataFrame(columns=['id', 'nationality']); record = pd.DataFrame(columns=['swimmer_id', 'event_id']); stadium = pd.DataFrame(columns=['name', 'id']); event = pd.DataFrame(columns=['id', 'stadium_id'])
stadium[stadium['id'].isin(event[event['id'].isin(record[record['swimmer_id'].isin(swimmer[swimmer['nationality'] == 'Australia']['id'])]['event_id'])]['stadium_id'])]['name']