Question: what is the name of the dolls that fit inside each other
[{'answer': 'A matryoshka doll'}, {'provenance': [{'wikipedia_id': '331080', 'title': 'Matryoshka doll', 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 316, 'bleu_score': 0.6207304132735241, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 14095151003733175875}, 'section': 'Section::::Abstract.'}]}]