Question: what is the name of the tallest building in london
[{'answer': 'The Shard', 'provenance': [{'wikipedia_id': '180342', 'title': 'List of tallest buildings and structures in London', 'start_paragraph_id': 1, 'start_character': 53, 'end_paragraph_id': 1, 'end_character': 62, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}]