Question: when did north vietnam unify with the south
[{'answer': '2 July 1976', 'provenance': [{'wikipedia_id': '202354', 'title': 'Vietnam', 'start_paragraph_id': 31, 'start_character': 3, 'end_paragraph_id': 31, 'end_character': 14, 'bleu_score': 1.0, 'section': 'Section::::History.:Reunification and reforms.\n'}]}]