Question: how many books in the little house on the prairie series
[{'answer': 'eight', 'provenance': [{'wikipedia_id': '6817404', 'title': 'List of Little House on the Prairie books', 'start_paragraph_id': 1, 'start_character': 49, 'end_paragraph_id': 1, 'end_character': 54, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '6817404', 'title': 'List of Little House on the Prairie books', 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 690, 'bleu_score': 0.9522287480520011, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 7188419360299479971}, 'section': 'Section::::Abstract.'}]}]