Question: when did the millennium dome became the o2 arena
[{'answer': '31 May 2005', 'provenance': [{'wikipedia_id': '39763', 'title': 'Millennium Dome', 'start_paragraph_id': 52, 'start_character': 43, 'end_paragraph_id': 52, 'end_character': 54, 'bleu_score': 1.0, 'section': 'Section::::The aftermath.:Redevelopment and rebranding as The O2.\n'}]}, {'provenance': [{'wikipedia_id': '39763', 'title': 'Millennium Dome', 'start_paragraph_id': 52, 'start_character': 0, 'end_paragraph_id': 52, 'end_character': 707, 'bleu_score': 0.984062469849008, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 6455542031328706906}, 'section': 'Section::::The aftermath.:Redevelopment and rebranding as The O2.\n'}]}]