Question: when did season 4 of madam secretary start
[{'answer': 'October 8 , 2017', 'provenance': [{'wikipedia_id': '55186550', 'title': 'Madam Secretary (season 4)', 'start_paragraph_id': 30, 'start_character': 46, 'end_paragraph_id': 30, 'end_character': 62, 'bleu_score': 1.0, 'section': 'Section::::Broadcast.\n'}]}]