Question: who is the lender of last resort in the us
[{'answer': 'a central bank', 'provenance': [{'wikipedia_id': '921278', 'title': 'Lender of last resort', 'start_paragraph_id': 8, 'start_character': 145, 'end_paragraph_id': 8, 'end_character': 159, 'bleu_score': 1.0, 'section': "Section::::Classical theory.:Thornton's foundations.\n"}]}, {'provenance': [{'wikipedia_id': '921278', 'title': 'Lender of last resort', 'start_paragraph_id': 1, 'start_character': 321, 'end_paragraph_id': 1, 'end_character': 1095, 'bleu_score': 0.669747292583965, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 7774714405183754390}, 'section': 'Section::::Abstract.'}]}]