Question: what are the names of the fifty shades of grey series
[{'answer': 'Fifty Shades of Grey', 'provenance': [{'wikipedia_id': '39934520', 'title': 'Fifty Shades (novel series)', 'start_paragraph_id': 1, 'start_character': 93, 'end_paragraph_id': 1, 'end_character': 113, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'answer': 'Fifty Shades Darker', 'provenance': [{'wikipedia_id': '39934520', 'title': 'Fifty Shades (novel series)', 'start_paragraph_id': 1, 'start_character': 124, 'end_paragraph_id': 1, 'end_character': 143, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'answer': 'Fifty Shades Freed', 'provenance': [{'wikipedia_id': '39934520', 'title': 'Fifty Shades (novel series)', 'start_paragraph_id': 1, 'start_character': 150, 'end_paragraph_id': 1, 'end_character': 168, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'answer': 'Grey', 'provenance': [{'wikipedia_id': '39934520', 'title': 'Fifty Shades (novel series)', 'start_paragraph_id': 1, 'start_character': 109, 'end_paragraph_id': 1, 'end_character': 113, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'answer': 'Darker', 'provenance': [{'wikipedia_id': '39934520', 'title': 'Fifty Shades (novel series)', 'start_paragraph_id': 1, 'start_character': 137, 'end_paragraph_id': 1, 'end_character': 143, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}]