Question: who was the first leader of unified england
[{'answer': 'King Æthelstan', 'provenance': [{'wikipedia_id': '407950', 'title': 'Kingdom of England', 'start_paragraph_id': 14, 'start_character': 411, 'end_paragraph_id': 14, 'end_character': 425, 'bleu_score': 1.0, 'section': 'Section::::History.:Anglo-Saxon England.\n'}]}, {'provenance': [{'wikipedia_id': '407950', 'title': 'Kingdom of England', 'start_paragraph_id': 14, 'start_character': 0, 'end_paragraph_id': 14, 'end_character': 435, 'bleu_score': 0.9720210313175831, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 7264682019775599809}, 'section': 'Section::::History.:Anglo-Saxon England.\n'}]}]