Question: when did the constituent assembly hold its first session
[{'answer': 'May 28 , 2008', 'provenance': [{'wikipedia_id': '16859155', 'title': '1st Nepalese Constituent Assembly', 'start_paragraph_id': 2, 'start_character': 262, 'end_paragraph_id': 2, 'end_character': 275, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '16859155', 'title': '1st Nepalese Constituent Assembly', 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 519, 'bleu_score': 0.9766041382465441, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 8925127381687582376}, 'section': 'Section::::Abstract.'}]}]