Question: what is the oldest stamp in the world
[{'answer': 'The Penny Black', 'provenance': [{'wikipedia_id': '193260', 'title': 'Penny Black', 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 15, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '193260', 'title': 'Penny Black', 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 241, 'bleu_score': 0.762629290207528, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 14881679626625603737}, 'section': 'Section::::Abstract.'}]}]