Question: who is the current chief executive of nhs england
[{'answer': 'Simon Stevens', 'provenance': [{'wikipedia_id': '39156670', 'title': 'NHS England', 'start_paragraph_id': 7, 'start_character': 134, 'end_paragraph_id': 7, 'end_character': 147, 'bleu_score': 1.0, 'section': 'Section::::History.\n'}]}]