Question: what is the purpose of a leaf spring
[{'answer': 'suspension in wheeled vehicles', 'provenance': [{'wikipedia_id': '600122', 'title': 'Leaf spring', 'start_paragraph_id': 1, 'start_character': 63, 'end_paragraph_id': 1, 'end_character': 93, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '600122', 'title': 'Leaf spring', 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 354, 'bleu_score': 0.923768200931469, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 18232855748460605007}, 'section': 'Section::::Abstract.'}]}]