Question: when did vatican city become a sovereign state
[{'answer': '7 June 1929', 'provenance': [{'wikipedia_id': '32408', 'title': 'Vatican City', 'start_paragraph_id': 23, 'start_character': 333, 'end_paragraph_id': 23, 'end_character': 344, 'bleu_score': 1.0, 'section': 'Section::::History.:Lateran treaties.\n'}]}, {'provenance': [{'wikipedia_id': '32408', 'title': 'Vatican City', 'start_paragraph_id': 23, 'start_character': 0, 'end_paragraph_id': 23, 'end_character': 453, 'bleu_score': 0.9738505480425671, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 4197192436086016014}, 'section': 'Section::::History.:Lateran treaties.\n'}]}]