Question: which is the world's largest company in terms of revenue
[{'answer': 'Walmart', 'provenance': [{'wikipedia_id': '997455', 'title': 'List of largest companies by revenue', 'start_paragraph_id': 1, 'start_character': 193, 'end_paragraph_id': 1, 'end_character': 200, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '997455', 'title': 'List of largest companies by revenue', 'section': 'Section::::Abstract.', 'start_paragraph_id': 1, 'end_paragraph_id': 1, 'meta': {'evidence_span': ["Walmart has been the world's largest company by revenue since 2014, with $514 billion in revenue in 2019.", 'This list comprises the world\'s largest companies by consolidated revenue as of 2019, according to the "Fortune" Global 500 latest tally published on July 22, 2019. American retail corporation Walmart has been the world\'s largest company by revenue since 2014, with $514 billion in revenue in 2019.', "American retail corporation Walmart has been the world's largest company by revenue since 2014, with $514 billion in revenue in 2019"]}}]}]