Question: who sings with robert plant on the battle of evermore
[{'answer': 'Sandy Denny', 'provenance': [{'wikipedia_id': '202579', 'title': 'The Battle of Evermore', 'start_paragraph_id': 1, 'start_character': 65, 'end_paragraph_id': 1, 'end_character': 76, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '202579', 'title': 'The Battle of Evermore', 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 235, 'bleu_score': 0.9493253852526031, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 18218368168026580840}, 'section': 'Section::::Abstract.'}]}]