Question: What musical style is performed by the professional group 'Straight No Chaser' who gained recognition when a video of theirs, 'The 12 days of Christmas' went viral and who subsequently landed a five-album deal before changing their name to Another Round?
{'answer': 'a cappella', 'supporting_facts': [['Another Round (group)', 0], ['Straight No Chaser (group)', 0], ['Straight No Chaser (group)', 1]]}