Question: how many episodes of blue planet 2 will there be
[{'answer': '7', 'provenance': [{'wikipedia_id': '53265861', 'title': 'Blue Planet II', 'start_paragraph_id': 1, 'start_character': 23, 'end_paragraph_id': 1, 'end_character': 24, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}]