Question: what is a characteristic of the invasion novel
[{'answer': 'hypothetical invasions by foreign powers', 'provenance': [{'wikipedia_id': '3243257', 'title': 'Invasion literature', 'start_paragraph_id': 1, 'start_character': 424, 'end_paragraph_id': 1, 'end_character': 464, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}]