Question: what are the blue boxes at the post office
[{'answer': 'mail collection boxes', 'provenance': [{'wikipedia_id': '1354475', 'title': 'Post box', 'start_paragraph_id': 11, 'start_character': 65, 'end_paragraph_id': 11, 'end_character': 86, 'bleu_score': 1.0, 'section': 'Section::::History of post boxes.:North America.\n'}]}]