Question: what is the name of the main muscle that forms the calf
[{'answer': 'gastrocnemius muscle', 'provenance': [{'wikipedia_id': '2289425', 'title': 'Gastrocnemius muscle', 'start_paragraph_id': 1, 'start_character': 4, 'end_paragraph_id': 1, 'end_character': 24, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '2289425', 'title': 'Gastrocnemius muscle', 'start_paragraph_id': 1, 'start_character': 26, 'end_paragraph_id': 1, 'end_character': 395, 'bleu_score': 0.688572764556831, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 14025214275603935289}, 'section': 'Section::::Abstract.'}]}]