Question: who played george gershwin in rhapsody in blue
[{'answer': 'Robert Alda', 'provenance': [{'wikipedia_id': '4311328', 'title': 'Rhapsody in Blue (film)', 'start_paragraph_id': 3, 'start_character': 9, 'end_paragraph_id': 3, 'end_character': 20, 'bleu_score': 1.0, 'section': 'Section::::Production background.\n'}]}, {'provenance': [{'wikipedia_id': '4311328', 'title': 'Rhapsody in Blue (film)', 'start_paragraph_id': 9, 'start_character': 0, 'end_paragraph_id': 9, 'end_character': 42, 'bleu_score': 0.6147881529512641, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 4885672895152939447}, 'section': 'Section::::Cast.\n'}]}]