Question: how many hat tricks has messi scored in the champions league
[{'answer': '7', 'provenance': [{'wikipedia_id': '41532657', 'title': 'List of UEFA Champions League hat-tricks', 'start_paragraph_id': 5, 'start_character': 295, 'end_paragraph_id': 5, 'end_character': 296, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}]