Question: when did batman first appeared in comic books
[{'answer': 'May 1939', 'provenance': [{'wikipedia_id': '3622838', 'title': 'Batman (comic book)', 'start_paragraph_id': 1, 'start_character': 182, 'end_paragraph_id': 1, 'end_character': 190, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '3622838', 'title': 'Batman (comic book)', 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 445, 'bleu_score': 0.885496993541598, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 15677409793631802596}, 'section': 'Section::::Abstract.'}]}]