Question: what episode is the flash and supergirl crossover musical
[{'answer': "`` Duet ''"}, {'provenance': [{'wikipedia_id': '53517522', 'title': 'Duet (The Flash)', 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 910, 'bleu_score': 0.924149671592795, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 9969992335538682652}, 'section': 'Section::::Abstract.'}]}]