Question: who proposed a counter proposal to the wilmot proviso
[{'answer': 'Lewis Cass', 'provenance': [{'wikipedia_id': '55576', 'title': 'Wilmot Proviso', 'start_paragraph_id': 14, 'start_character': 454, 'end_paragraph_id': 14, 'end_character': 464, 'bleu_score': 1.0, 'section': 'Section::::Introduction and debate on the proviso.\n'}]}, {'provenance': [{'wikipedia_id': '55576', 'title': 'Wilmot Proviso', 'start_paragraph_id': 14, 'start_character': 0, 'end_paragraph_id': 14, 'end_character': 688, 'bleu_score': 0.9636229844862961, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 7048144629280632239}, 'section': 'Section::::Introduction and debate on the proviso.\n'}]}]