Question: who has played in the most consecutive nba finals
[{'answer': 'Boston Celtics', 'provenance': [{'wikipedia_id': '24652118', 'title': 'List of NBA franchise post-season streaks', 'start_paragraph_id': 2, 'start_character': 549, 'end_paragraph_id': 2, 'end_character': 563, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}]