Question: where does the phrase swan song come from
[{'answer': 'ancient Greece', 'provenance': [{'wikipedia_id': '410604', 'title': 'Swan song', 'start_paragraph_id': 1, 'start_character': 438, 'end_paragraph_id': 1, 'end_character': 452, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '410604', 'title': 'Swan song', 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 536, 'bleu_score': 0.880398529492844, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 10021870574490059816}, 'section': 'Section::::Abstract.'}]}]