Question: what is the movie birth of a nation about
[{'answer': 'the story of Nat Turner', 'provenance': [{'wikipedia_id': '46385738', 'title': 'The Birth of a Nation (2016 film)', 'start_paragraph_id': 1, 'start_character': 77, 'end_paragraph_id': 1, 'end_character': 100, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'answer': 'slave rebellion in Southampton County , Virginia'}, {'provenance': [{'wikipedia_id': '46385738', 'title': 'The Birth of a Nation (2016 film)', 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 671, 'bleu_score': 0.9486604584788991, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 210360020464508872}, 'section': 'Section::::Abstract.'}]}]