Question: what is the symbol on superman's chest
[{'answer': 'letter S', 'provenance': [{'wikipedia_id': '6991147', 'title': 'Superman logo', 'start_paragraph_id': 4, 'start_character': 73, 'end_paragraph_id': 4, 'end_character': 82, 'bleu_score': 1.0, 'section': 'Section::::Evolution of the symbol.\n'}]}, {'provenance': [{'wikipedia_id': '6991147', 'title': 'Superman logo', 'start_paragraph_id': 4, 'start_character': 0, 'end_paragraph_id': 4, 'end_character': 370, 'bleu_score': 0.9712154609069981, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 15850036616165518741}, 'section': 'Section::::Evolution of the symbol.\n'}]}]