Question: when does april come on grey's anatomy
[{'answer': "`` Invasion ''"}, {'provenance': [{'wikipedia_id': '27660054', 'title': 'April Kepner', 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 897, 'bleu_score': 0.6510022938286201, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 1654423520962046967}, 'section': 'Section::::Abstract.'}]}]