Question: when did tesla come to the united states
[{'answer': '1884', 'provenance': [{'wikipedia_id': '21473', 'title': 'Nikola Tesla', 'start_paragraph_id': 2, 'start_character': 267, 'end_paragraph_id': 2, 'end_character': 271, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '21473', 'title': 'Nikola Tesla', 'start_paragraph_id': 2, 'start_character': 0, 'end_paragraph_id': 2, 'end_character': 869, 'bleu_score': 0.9563468294086971, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 15831276138856749624}, 'section': 'Section::::Abstract.'}]}]