Question: when is season finale of americas got talent 2017
[{'answer': 'September 20 , 2017', 'provenance': [{'wikipedia_id': '51620827', 'title': "America's Got Talent (season 12)", 'start_paragraph_id': 51, 'start_character': 32, 'end_paragraph_id': 51, 'end_character': 51, 'bleu_score': 1.0, 'section': 'Section::::Finals.\n'}]}, {'provenance': [{'wikipedia_id': '51620827', 'title': "America's Got Talent (season 12)", 'start_paragraph_id': 3, 'start_character': 0, 'end_paragraph_id': 3, 'end_character': 375, 'bleu_score': 0.9180466554652991, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 6310273002285257009}, 'section': 'Section::::Abstract.'}]}]