Question: who sings with taylor swift on everything has changed
[{'answer': 'Ed Sheeran', 'provenance': [{'wikipedia_id': '37807230', 'title': 'Everything Has Changed', 'start_paragraph_id': 1, 'start_character': 115, 'end_paragraph_id': 1, 'end_character': 125, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}]