แชมป์เปี้ยนคนไหนมี LLWS รอบแบ่งกลุ่มในรัสเซลวิลล์?
Which champion has a Group Stage LLWS in Russellville?
df = pd.DataFrame(columns=['champion', 'llws', 'city'])
df[(df['llws'] == 'group stage') & (df['city'] == 'russellville')]['champion']