Question: how long did it take to film nightmare before christmas
[{'answer': 'two years', 'provenance': [{'wikipedia_id': '403227', 'title': 'The Nightmare Before Christmas', 'start_paragraph_id': 28, 'start_character': 450, 'end_paragraph_id': 28, 'end_character': 459, 'bleu_score': 1.0, 'section': 'Section::::Production.:Filming.\n'}]}, {'provenance': [{'wikipedia_id': '403227', 'title': 'The Nightmare Before Christmas', 'start_paragraph_id': 28, 'start_character': 0, 'end_paragraph_id': 28, 'end_character': 729, 'bleu_score': 0.9676402440805071, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 10373157769598529862}, 'section': 'Section::::Production.:Filming.\n'}]}]