Question: where is calcium stored in a muscle cell
[{'answer': 'sarcoplasmic reticulum ( SR )', 'provenance': [{'wikipedia_id': '423439', 'title': 'Sarcoplasmic reticulum', 'start_paragraph_id': 1, 'start_character': 4, 'end_paragraph_id': 1, 'end_character': 34, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '423439', 'title': 'Sarcoplasmic reticulum', 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 1081, 'bleu_score': 0.988668097924812, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 5120565034482612774}, 'section': 'Section::::Abstract.'}]}]