Question: halloween has roots in a celtic festival called what
[{'answer': 'Samhain', 'provenance': [{'wikipedia_id': '13855', 'title': 'Halloween', 'start_paragraph_id': 2, 'start_character': 136, 'end_paragraph_id': 2, 'end_character': 143, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '13855', 'title': 'Halloween', 'start_paragraph_id': 2, 'start_character': 0, 'end_paragraph_id': 2, 'end_character': 386, 'bleu_score': 0.9645876452711911, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 800668907242822778}, 'section': 'Section::::Abstract.'}]}]