Question: who was president when the iron curtain fell
[{'answer': 'Harry S. Truman', 'provenance': [{'wikipedia_id': '18953051', 'title': 'Iron Curtain', 'start_paragraph_id': 18, 'start_character': 115, 'end_paragraph_id': 18, 'end_character': 130, 'bleu_score': 1.0, 'section': 'Section::::Pre–Cold War usage.\n'}]}, {'provenance': [{'wikipedia_id': '18953051', 'title': 'Iron Curtain', 'start_paragraph_id': 18, 'start_character': 0, 'end_paragraph_id': 18, 'end_character': 629, 'bleu_score': 0.9491353855517691, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 1752182637712560854}, 'section': 'Section::::Pre–Cold War usage.\n'}]}]