Question: how many joint committees are there in the senate
[{'answer': 'four', 'provenance': [{'wikipedia_id': '533853', 'title': 'List of United States Senate committees', 'start_paragraph_id': 10, 'start_character': 10, 'end_paragraph_id': 10, 'end_character': 14, 'bleu_score': 1.0, 'section': 'Section::::Committee classes.:Standing committees.\n'}]}, {'provenance': [{'wikipedia_id': '533853', 'title': 'List of United States Senate committees', 'start_paragraph_id': 14, 'start_character': 0, 'end_paragraph_id': 14, 'end_character': 287, 'bleu_score': 0.9560167778278961, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 13328138764909009062}, 'section': 'Section::::Committee classes.:Joint committees.\n'}]}]