Question: who sings the theme song for republic of doyle
[{'answer': 'Great Big Sea', 'provenance': [{'wikipedia_id': '604745', 'title': 'Great Big Sea', 'start_paragraph_id': 0, 'start_character': 0, 'end_paragraph_id': 0, 'end_character': 13, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '604745', 'title': 'Great Big Sea', 'start_paragraph_id': 22, 'start_character': 0, 'end_paragraph_id': 22, 'end_character': 99, 'bleu_score': 0.8914703664390791, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 3631393069901460788}, 'section': 'Section::::History.:Later career.\n'}]}]