Question: the level of the national debt is limited by
[{'answer': 'debt ceiling', 'provenance': [{'wikipedia_id': '322221', 'title': 'National debt of the United States', 'start_paragraph_id': 6, 'start_character': 661, 'end_paragraph_id': 6, 'end_character': 673, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '322221', 'title': 'National debt of the United States', 'start_paragraph_id': 6, 'start_character': 0, 'end_paragraph_id': 6, 'end_character': 673, 'bleu_score': 0.9829771687435411, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 4414921165375449938}, 'section': 'Section::::Abstract.'}]}]