Question: where is the myelin sheath located on a neuron
[{'answer': 'the axon', 'provenance': [{'wikipedia_id': '19319', 'title': 'Myelin', 'start_paragraph_id': 1, 'start_character': 483, 'end_paragraph_id': 1, 'end_character': 491, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}]