Question: when was the first handheld mobile phone invented
[{'answer': 'April 3 , 1973', 'provenance': [{'wikipedia_id': '1245539', 'title': 'History of mobile phones', 'start_paragraph_id': 44, 'start_character': 162, 'end_paragraph_id': 44, 'end_character': 176, 'bleu_score': 1.0, 'section': 'Section::::Handheld mobile phone.\n'}]}, {'provenance': [{'wikipedia_id': '1245539', 'title': 'History of mobile phones', 'start_paragraph_id': 44, 'start_character': 0, 'end_paragraph_id': 44, 'end_character': 507, 'bleu_score': 0.789360289761021, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 7049389290257247035}, 'section': 'Section::::Handheld mobile phone.\n'}]}]