Question: who played cosmo in singin in the rain
[{'answer': "Donald O'Connor", 'provenance': [{'wikipedia_id': '1883157', 'title': "Singin' in the Rain", 'start_paragraph_id': 1, 'start_character': 144, 'end_paragraph_id': 1, 'end_character': 159, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '1883157', 'title': "Singin' in the Rain", 'start_paragraph_id': 13, 'start_character': 0, 'end_paragraph_id': 13, 'end_character': 149, 'bleu_score': 0.9067110266941041, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 14961041321130501624}, 'section': 'Section::::Cast.\n'}]}]