Question: how many decks of cards are used to play canasta
[{'answer': 'two', 'provenance': [{'wikipedia_id': '87099', 'title': 'Canasta', 'start_paragraph_id': 1, 'start_character': 149, 'end_paragraph_id': 1, 'end_character': 152, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '87099', 'title': 'Canasta', 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 479, 'bleu_score': 0.9589524033887861, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 13294488386532229960}, 'section': 'Section::::Abstract.'}]}]