Question: what type of government system does nigeria have
[{'answer': 'a federal republic', 'provenance': [{'wikipedia_id': '21387', 'title': 'Federal government of Nigeria', 'start_paragraph_id': 2, 'start_character': 11, 'end_paragraph_id': 2, 'end_character': 29, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '21387', 'title': 'Federal government of Nigeria', 'start_paragraph_id': 2, 'start_character': 0, 'end_paragraph_id': 2, 'end_character': 987, 'bleu_score': 0.9715305700167061, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 9831510207037706010}, 'section': 'Section::::Abstract.'}]}]