Question: when was the first modern postage stamp released
[{'answer': '1840', 'provenance': [{'wikipedia_id': '25126', 'title': 'Postage stamp', 'start_paragraph_id': 31, 'start_character': 192, 'end_paragraph_id': 31, 'end_character': 196, 'bleu_score': 1.0, 'section': 'Section::::History.\n'}]}]