Question: when did david luiz go back to chelsea
[{'answer': 'August 2016', 'provenance': [{'wikipedia_id': '9262402', 'title': 'David Luiz', 'start_paragraph_id': 2, 'start_character': 486, 'end_paragraph_id': 2, 'end_character': 497, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '9262402', 'title': 'David Luiz', 'start_paragraph_id': 2, 'start_character': 0, 'end_paragraph_id': 2, 'end_character': 528, 'bleu_score': 0.7806257210224921, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 12359441871829895438}, 'section': 'Section::::Abstract.'}]}]