Question: what is the highest rank of black belt in taekwondo
[{'answer': '9th dan', 'provenance': [{'wikipedia_id': '23345581', 'title': 'List of taekwondo grandmasters', 'start_paragraph_id': 4, 'start_character': 33, 'end_paragraph_id': 4, 'end_character': 41, 'bleu_score': 1.0, 'section': 'Section::::Kukkiwon (World Taekwondo).\n'}]}, {'provenance': [{'wikipedia_id': '23345581', 'title': 'List of taekwondo grandmasters', 'start_paragraph_id': 4, 'start_character': 0, 'end_paragraph_id': 4, 'end_character': 126, 'bleu_score': 0.8970773746801091, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 14689375838671183534}, 'section': 'Section::::Kukkiwon (World Taekwondo).\n'}]}]