Question: what star wars movie does yoda first appear in
[{'answer': 'The Empire Strikes Back', 'provenance': [{'wikipedia_id': '63171', 'title': 'Yoda', 'start_paragraph_id': 1, 'start_character': 121, 'end_paragraph_id': 1, 'end_character': 144, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '63171', 'title': 'Yoda', 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 566, 'bleu_score': 0.769294753373683, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 3420507350595332562}, 'section': 'Section::::Abstract.'}]}]