Question: who did we buy the gadsden purchase from
[{'answer': 'Mexico', 'provenance': [{'wikipedia_id': '143163', 'title': 'Gadsden Purchase', 'start_paragraph_id': 1, 'start_character': 31, 'end_paragraph_id': 1, 'end_character': 37, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}]