Question: how many series of father brown is there
[{'answer': '6', 'provenance': [{'wikipedia_id': '36623250', 'title': 'Father Brown (2013 TV series)', 'start_paragraph_id': 51, 'start_character': 671, 'end_paragraph_id': 51, 'end_character': 672, 'bleu_score': 1.0, 'section': 'Section::::Production.:Filming.\n'}]}]