Question: who is the second richest person of the world
[{'answer': 'Warren Buffett', 'provenance': [{'wikipedia_id': '33331732', 'title': "The World's Billionaires", 'start_paragraph_id': 16, 'start_character': 280, 'end_paragraph_id': 16, 'end_character': 294, 'bleu_score': 1.0, 'section': 'Section::::Annual rankings.:2016.\n'}]}]