Question: who sings the theme song on empty nest
[{'answer': 'Billy Vera', 'provenance': [{'wikipedia_id': '680020', 'title': 'Empty Nest', 'start_paragraph_id': 77, 'start_character': 100, 'end_paragraph_id': 77, 'end_character': 110, 'bleu_score': 1.0, 'section': 'Section::::Production notes.:Theme song.\n'}]}, {'provenance': [{'wikipedia_id': '680020', 'title': 'Empty Nest', 'start_paragraph_id': 77, 'start_character': 0, 'end_paragraph_id': 77, 'end_character': 394, 'bleu_score': 0.970362113628587, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 13356777547094218493}, 'section': 'Section::::Production notes.:Theme song.\n'}]}]