Question: where was trick or treat for unicef started
[{'answer': 'on Halloween 1950', 'provenance': [{'wikipedia_id': '19762605', 'title': 'Trick-or-Treat for UNICEF', 'start_paragraph_id': 1, 'start_character': 112, 'end_paragraph_id': 1, 'end_character': 129, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '19762605', 'title': 'Trick-or-Treat for UNICEF', 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 583, 'bleu_score': 0.940965794090011, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 3094768270280280867}, 'section': 'Section::::Abstract.'}]}]